Their positions won't change, for the most part.
But their positions will change from progressive to conservative... to conserve the progress in their lifetimes.
(ex: if you support gay marriage, you are now a conservative on the issue... because you want to conserve the nationwide legal status of same-sex marriage, not change it.)
No. Supporting legalized abortion isn't conservative just because of Roe.
You two proved that answering this question requires answering another question first. Namely, what is "conservatism?"
If you're talking about "conservative" as preserving the status quo, that has and for the foreseable future will continue to move leftward (especially on social issues), so people will appear to move rightward with age. For example, if person A is pro-SSM, and person B is anti-SSM, A would look like a crazed extremist 30 years ago, while B's position would've been shared with most people, both of them would appear somewhat mainstream now, while in 30 years B would look like the crazed extremist, and A wouldn't raise any eyebrows.
However, the common US-definition of "conservative" is basically right-wing--an odd blend of moderate economic libertarianism, social authoritarianism with a nuance here or there, military interventionism, and some level of nationalism. I see no reason why young people would gravitate towards the ridiculous #2 and #4, I'm trying to be optimistic but am ultimately doubtful they gravitate towards #1, and regarding #3, a proper millenial (pre-2000) would remember the Iraq disaster, but I could see the post-millenials more susceptible to supporting war if it was marketed as another patriotic mission to slay the boogeyman.
So, basically, no--millenials will not, in general, change their views to 2016 mainstream conservatism, but mainstream conservatism will probably meet them on most things, sooner or later.
