Could George Hackenschmidt be a big time great WWE Superstar in 2021?

If he would have taken drama school, maybe. But then again for that to happen he would have needed a time machine the go more then a century further.

Today, no I don't think so. He was very bland a wrestler and relied strictly on stand up power moves. Though he was well built, unless he adapted to today's wrestling style I don't think he would. Though there are a lot of power wrestlers, especially in WWE Vince likes those looking like monsters, huge in size. George wasn't tremendously tall. 

While WWE now signs and pushes more wrestlers that are smaller in stature, it's still not Vince's preference of the type of wrestler he likes. So I would have to say no he wouldn't, there would have to be something that extraordinarily stands out about him for Vince to even give him a chance.