Could they become a thing of the past
Frankly, no amount of high ISO performance is any use at all for this sort of thing.
Here's one I prepared earlier .....


I've got a K7, but I can't imagine how any camera could get this shot just by having far higher ISO performance. Here the ambient window sunlight is from behind (creating the rim lighting - controlled by shutter speed), and the frontal lighting is a single Pentax AF540-FGZ on a stand fired into a white reflective umbrella.

My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver

No, I don't think so. This is because flash is not really just about providing artificial lighting in dark conditions. It is about balancing the lighting in difficult situations (like the High Speed Sync outdoor sunshine scenes I like so much) and creating directional and targeted light. It is about gaining control over the lighting of your subjects for creative purposes and to create real quality in illumination. And it allows creative control independently over the ambient exposure and subject exposure, including the colour balancing.
Frankly, no amount of high ISO performance is any use at all for this sort of thing.
Here's one I prepared earlier .....


I've got a K7, but I can't imagine how any camera could get this shot just by having far higher ISO performance. Here the ambient window sunlight is from behind (creating the rim lighting - controlled by shutter speed), and the frontal lighting is a single Pentax AF540-FGZ on a stand fired into a white reflective umbrella.

What he said
Everything Changes
http://www.flickr.com/photos/arleimages/
ISO performance has plateaued over recent years btw. Mainly due to the stupid MegaPixel Race that panders to some photographers wanting to see every Higgs Boson in their pictures of a single tree in a field. The Pentax K-5 came out in 2010 and still hasn't been beaten in ISO performance, apart from a certain 12MP Full Frame camera and maybe some high end C and N exaMPLES
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
Not sure if what I've written makes sense, but essentially a flash allows you to 're light' a scene, regardless of it being bright or dark. A great example of this is to have a fast shutter speed to make the background dark, but use a flash to light your subject, making them 'pop' out from the background. This use of a flash, to shape the light to how you want it (rather than be hamstrung by it ~ 'natural light photographer') isn't going anywhere just because a cameras ISO abilities have improved.
But, for other use, such as street photography, where you want to be discrete, or other areas where a flash isn't appropriate or bright enough, then base level ISO ability is important.
So, agree with Nigel and above, but also acknowledge that there are times where more ISO ability is very useful. I personally don't see the base ISO abilities of modern day sensors getting much better (hasn't really improved in the last 5 years or so) unless someone is prepared to back off the MP race and provide larger pixels, such as the only 12MP Sony A7s. Personally I'd happily sacrifice some cropping ability for some base level ISO performance improvements.
That leaves the built-environment, and night urban scenes with artificial lighting. Here of course, long exposures and shorter high ISO exposures can be very effective, and for mobile dynamic low-light street photography high ISO performance would be great. BUT .... it does not resolve the issues of dynamic range in the scene, so you still have the problems caused by very bright hotspots from strong lights to balance against pitch black shadows, which will just turn into a muddy grey murk if overexposed. And the colour balance challenges can be great also, and again high ISO does not resolve that.
A classic case would be your night-time city-scape portrait. Your subject stands beside the river in relative darkness illuminated dimly by some tungsten street lamps .... and your lovely city skyline with its lights is behind. The classic flash approach here is the 'slow-sync' method .... a slow shutter speed to record the ambient background (camera supported) plus front fill flash on the subject. This gives the correct colour balance on the face as well as illumination, so you have two components to the exposure and the colour balance.
Now, if you eliminated the flash here because your camera has great high ISO performance, and you cranked up the ISO to give you a hand-holdable speed, what are the likely results? Well, because you're not actually doing anything to balance either the exposure or colour balance, then it would not be very good I'd suggest ..... if you metered for the dimly lit subject then you're still likely to underexpose your background, plus all you will do colour-wise is brighten up the tungsten lit subject and end up with a horrible orange face.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
For 'studio' type use where flash is used to produce multiple creative light sources that is a different matter yet even here is flash likely to persist? Flash really isn't desirable for this use either, it is just a more economical and cooler alternative to using modelling lights and more compact and convenient than using mirror and reflectors. Yet with better high ISO performance we could use smaller more compact mirrors and reflectors, or substitute modern high output LED sources for the flash and be able to properly see the lighting effects rather than guess how the flash will render it. So even for this purpose I imagine flash will become less important and prevalent.

philstaff
Member
Regards Ian