I'm with M2 on the .40 argument. No practical upside compared to 9mm with several drawbacks. I think a lot of people shoot .40 based on ego and hearsay wrt 9mm effectiveness. Just my opinion, though.
For you AR guys Palmetto State Armory is selling D&H mags for $90/10. Get 'em while you still can. I'd stock up on pistol mags as well.
Mag capacity and online ammo sales seem like pretty easy targets for legislation. Meaningful, common sense changes, know what I mean?