Magnification of one million times will be possible.

Waldemar Kaempffert : Science writer
In 1950, Popular Mechanics printed an article forecasting what everyday life would be like in AD 2000, including such luxuries as proton magniscopes allowing magnification of one million times.
The current best possible magnification is 1200x.

Waldemar Kaempffert, "Miracles You’ll See In The Next Fifty Years", Popular Mechanics. Feb 1950.