Comment by epsilonclose

I don't know. For a sufficiently large change, it isn't necessarily in your company's best interest to try to keep you happy. You have banked knowledge and skill in X. You have limited skill in Y but wish to learn. The loss of some fraction of X is always going to hurt the company more than your gain in Y will benefit them, so they are going to try to keep you doing as much of X as possible for as long as possible. If they were to let you switch to Y, they'd have to have already needed a junior person there, and they will now have to replace the person doing X. Maybe this is a small vs large company thing, but I think it is entirely possible to "typecast" yourself into a corner such that the best thing you can do if you want to pivot is jump ship.