I disagree. The game will not likely be double the length it already is before it ends so we are almost certainly more than two thirds of the way to the end and the MC still has two evolutions and multiple unknown tasks(very tough battles against higher level enemies) to go plus there will also be some incredibly tough battles along the way where the correct course of action will be to reject evolutions, plus the end game after that too. But all in all we are probably less than 10 major boss battles from the end of the game.I think its still way too early to be talking about MC level 4. I can definitely see a power spike after unlocking with the Golden Key, and the new developments that come with that higher Memory connection, but i think rolling that in with Level 4 will muddy the waters. Everyone else evolving sure, but considering we just had that Valravn "should I force an evo now" moment, that tells me to wait at least an arc or two before considering an evo.
Not to mention that earth is currently being invaded by all kinds of S and even some S+ level monsters. MC will probably need to be at least level 4 if he is to be anything but a fly on the wall of that conflict. So I very much suspect MC will be level 4 sooner rather than later. I would expect MC to evolve within the next three major boss fights.