That's the situation here in WA. now. Legal to own but you better have a receipt for your 20 rd. mags to prove you purchased those before the 10 rd mag restrictions went into effect if you want to use those in public. Everyone's going to address that differently but I just sold most of my >10 rd mags to avoid the hassle. I don't own an AR and never did. If I wanted a rifle for SD I'd probably just buy a SBR in a pistol caliber.
It's hard to know what the state will come up with when they move to restrict semi-auto rifles, but magazine restrictions seem to be the first step for legislators and the easiest one to pass. I've known WA was on that course for 5 years or more and purchased my pistols accordingly.
Edit.
I don't want a safe full of pistols, rifles or magazines I can't sell.