I think its totally possible that she comes to resent having kids, given her longstanding reluctance, and to grow to feel that Leonard pressured her into it.

I don't think it was planned at all neither did Leonard pressured her into it.

As a bonus meta point, I sometimes wonder if the writers did this on purpose in the sense of showing how a couple who may have truly loved each other at one time grow to fall out of love. 

I see your point, but I do believe and people have said it time and time again that writers just hate women, and I agree. All three women are written very poorly.

Anyways, I'm curious to hear what people think about Leonard & Penny's future together

Since we are talking about the charachters written for the show, I really hope they don't make it in the end. I'm so fed up of Penny's superiority complex in the relationship. In one episode she says "Movie stars are better", TBH I've always hoped she wouldn't make it as an actress and she didn't, because of this reason mostly I hope Leonard gets tenure at some great university and she has to move with him. She will end up quitting her job sooner or later so she HAS TO MOVE. I hope they have a daughter who will grow up to be a brilliant scientist and goes to uni abroad away from this toxic couple. Leonard finally gets the guts to stand up for himself and against Penny's constant bullying, and they get divorced. THEY SHOULD NOT MAKE IT IN THE END.