It's only too much if you are unwilling to do it. The advice I would give to you is to get the bare minimum break out clone up and running, then add all the extras. If you try to do it all at once you might get overwhelmed and never finish the project. This way you will at least end up with a working game, even if it is pretty basic.

To have different skins for a game is a nice idea. Makes it a bit like several games roled into one.

But in my experience the non professional game developer sitting alone at home has one big problem: limited resources. So you invest your precious time to not only create a game but also prepare for possible skins, which is an extra effort. And does this pay off? I bet it would not.

Only very popular software finds enough users to have some few people to really work on a new skin. I mean, you would have to ask 10000 people to find 1 interested. And this one is only interested if he can be sure that his work is released, used and noticed by many others. Frankly I don't see how a breakout clone could have this big impact.

From my experience (ok, my games use to be pretty lame, I guess) I estimate:
-you get maybe 5000 gamers to play your game over the first year
-you get 50 feedbacks (mainly here in this forum I guess)
-you get 0 user made skins

And that is when you are lucky :)
Call me an old, lazy pessimist, but I would concentrate on a nice, basic breakout game and try to get some interesting, original features with minimal effort. Don't count on euphoric users, they are so hard to find these days :)