Hardly. Nobody is currently exhausting the CPU capacity of even a normal computer currently and even if we did a 20x increase in load overnight, that still wouldn't even warm up most machines good enough to be always on.

The reasons full nodes are unpopular to run seem to be:

1. Uncontrollable bandwidth usage from sending people the chain

2. People don't run them all the time, then don't want to wait for them to catch up

The first can be fixed with better code (you can already easily opt out of uploading the chain, it's just not as fine-grained as desirable), and the second is fundamental to what full nodes do and how people work. For merchants, who are the most important demographic we want to be using full nodes, they can just keep it running all the time. No biggie.

 

This meme about datacenter-sized nodes has to die. The Bitcoin wiki is down right now, but I showed years ago that you could keep up with VISA on a single well specced server with today's technology. Only people living in a dreamworld think that Bitcoin might actually have to match that level of transaction demand with today's hardware. As noted previously, "too many users" is simply not a problem Bitcoin has .... and may never have!