Wouldn't it be exactly the same as with super resolution? It's not just a crutch for poorly optimized games, but something with a known overhead cost the developers could build around if it was deemed a better use of resources. GPU power seems likely to continue increasing at a faster pace than display resolution, so as time goes on the relative cost of interpolated frames will become more and more appealing.
Oh, I totally think so.
Super Resolution is a good example - to a gamer on PC it seems like free performance. You tweak knobs until you get the visual presentation you like, then turn on super resolution and boom, more frames. PC gamers don't have the option of implementing new, custom shaders to take advantage of their particular hardware, which means while tweaking settings, using 100% of their resources basically isn't an option, and on big hardware, DLSS is very low cost.
To a developer on a console, Super Resolution absolutely has a cost that needs to be budgeted around, just like everything else, and developers have the ability to optimize their game to eke out every last drop of perf. And because NG itself is small, DLSS's cost is relatively high. That's why I don't expect to see a lot of 4K DLSS games. Not because it's not doable, but because I think the average developer will decide that "4k but Low graphics settings everywhere" is less attractive than "1440p, but medium to high graphics settings everywhere."
For Frame Gen, it's the same question - when will turning it on be worth it, over the other places you could use that performance? Right now, Frame Gen is only possible with FSR, which means losing DLSS for just a couple of extra frames. Considering that DLSS's lower presets look as good or better than FSR's higher ones, that sounds like a very bad trade.
In fact, I don't think you even get those extra frames in most cases. DLSS looks as good as FSR, even when DLSS is running at a lower internal resolution. So why not do that to get frame rate up? I just don't think the shit is worth the shake.
Who knows what 2031 will bring, maybe the trade-offs will change. But the technology as it exists now, doesn't offer a good path forward on NG hardware. Perhaps eventually Nvidia will open FG up to these older cards, but I think we're still talking about sub-60fps gaming. And as I was trying to explain, the problems for FG on lower frame rates isn't a matter of optimization, it's actually baked into the core design.