Could they become a thing of the past

With cameras offering such good ISO performance now do forum members ever see the use of flash becoming a thing of the past.
Regards Ian

What he said

Yup, what Nigel said.

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

Agree with Nigel, but with the exception that if you are using flash to ONLY give some additional lighting to a dark scene, then better ISO performance would allow you to work later into the day before the flash needs to come out.

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.

I feel there are relatively few 'dark' situations where simply cranking up the sensitivity is any sort of quality solution. There are very limited environments where low or zero natural lighting would give nice results anyway .... for example, in a landscape, if there's no sunlight falling somewhere in the scene, then long exposures (or high ISO shorter exposures) don't usually make it very interesting. You're just photographing a shadow expanse .... with no light there's no photograph.

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.