The low end, the casuals....
People that want 4k and the sharpest image quality, and their games to look and play the best (input lag ect) will all still buy physical hardware.
Same with people that have data caps or not the fastest internet... or who live too far from a server farm, makeing the experiance not so great.
You talk as if 20 years from now internet speeds will be stuck at the same rates as today. In the next 10-20 years the leap in speeds will be huge, just like the leap we saw from 1998-2018 period. This is not something that will happen overnight, but it will certainly grow and solidify in the next 2 decades.
In the cities this is likely. Outside of them is another story. I live 15 minutes from a town of 25,000 who've had cable internet that has constantly been upgraded over the years, and around 4 years ago we just got the ability to sign up for 5.0 mbps DSL. That lasted about 6 months before the speed started dropping as more and more signed on. After a couple years we were only getting around 2 mbps on average, 1 mbps during peak. It took almost 2 years to get the problem 'solved'. The only reason it 'got solved' recently, was because another smaller ISP ran fiber through the general area, and stole enough customers to allow the remaining customers who couldn't get fiber, to be able to get their full 5 mbps speed at all times. Ping went from 250ms-500ms, down to 15ms-75ms as well. The local technician, who likes to game, and doesn't even live that far away, relies on satellite because he can only get dial up still for a hard line.
I also made a point to go to the local meeting for that ISP and ask when and if they had any plans to bring fiber this way, since nobody else is going to, and they told me I'd better just move because everyone outside of dense enough towns is getting left behind. They made sure to point out that wasn't just them talking, that's the industry. Their actually part of a larger group that's planning to use Gov funding to lay fiber over a massive area for 3 million people, and they said not only are the people in charge clueless, but the big telecom companies are making it extra hard and slowing the process as much as possible so they don't have to compete on prices since they will no longer own the lines themselves. Those oh so useful slow DSL or dial up lines...
The cities are probably the larger portion of the existing gaming market, but dedicated hardware is going to have to stay around for a long time or gaming companies are going to lose and upset those less dense, non urban dwelling customers. Plus emerging markets would all be lost since they won't have strong enough internet yet either.