Catch-up is, and always has been possible

[MooCow]

If we look at any character progression, and assume that it resembles some some function of time f(t), and then compare it to another's characters progression g(t) we will get the expression f(t)/g(t).
At any arbitrary time we can compare the two values: 10/5 = 2, thus Player 1 is twice as far as Player 2

For any polynomial growth (x^n) it can be shown that the limit as t approaches infinity f(c + t)/g(t) = f(t)/g(t), and if f(t) and g(t) are the same function, then the result will be equal to 1.
This can be simply thought like this: Eventually, the differences between two players that use similar growth methods will become trivial. Eventually, even a billion LP difference only amounts to a few stat points.

Even if your growth is accelerating this will still hold true, it will simply take longer than if it wasn't.

The real question is how long is a reasonable amount of time to catch up. How long should it take to catch up to a head start?