At this point I'm not really concerned about the rifles being outright banned, and if there is an outright ban I'd assume that getting uppers and other parts to actually build out those lowers wouldn't be very easy.
What I am trying to stock up on at this point is magazines. I just placed a $200 order with AIM Surplus for some more Pmags (and a few other Magpul goodies
). If legislation were attempted I don't believe they would go straight for outright bans on guns, but I do believe they would attempt things like magazine capacity limits and other "common sense", as they like to call it, regulations.