1. I don’t think these voters will change their political leanings very significantly. I presume as part of their civics education, that they were required to look into each party’s platform before voting. Whose to say that they don’t shift more leftwards, once they get out of being in school and realize how screwed their generation is?
2. To me, party platforms shifting leftwards over time is unlikely, as our current political culture is becoming more right leaning (e.g., carbon pricing disinformation, eating bugs disinformation, anti-vaccines). And our winner-take-all electoral system makes it relatively easy for the political establishment to maintain a stranglehold on power.
3. I think that left leaning parties will grow, yes.

I think the bigger concern is if these voters become apathetic to voting, due to how unfair it is.