There is nothing wrong with that sentence.

The use of "one" is an old style of language, when now used, gives an air of over formality. **Try** "Even if a person studies to an old age, they will never learn everything." or "You will never stop learning." "There is always something to learn." -->In English language (American), always try to say more with less.<-- **Revised** "One can never stop learning." [Common American phrase used formally as a philosophical conjecture].

It should read like this: Even if one studies to an old age,one will never FINISH learning. "will never finishing" is not the correct form for the future tense. will + verb = the correct form