Having nothing behind Dez, who has his share of injury history, and Beasley who's limited to strictly a slot receiver has put them in a bit of a pickle. I don't think there's any way they go into the draft without addressing it with someone who is at least a capable starter. That's probably going to look something similar to what Williams will be looking at with the risk of being an unknown. The real question is, is someone like Garcon or Stills worth the upgrade from Williams with the additional 3 million AAV and 10-15 million guaranteed? I think so, but it doesn't matter what we think.
I think they at least bring back Butler on a 1 year deal and try to keep Williams at that 5.5-6.5 per year range. If they can keep the guarantees low, they could move on from him in 2 years with minimal implications. This would hopefully allow them to address the defense through the draft and buy them a couple of seasons before they are needing a complete revamp of the position. Anything more than that though and we probably see a lower tier FA(along with Butler) and a 2nd-3rd Rd pick spent on a WR. Even then, I'm not sure that the offense doesn't take a step back with the looming risk of a significant step back if Dez or Beasley gets hurt.
Everyone is so focused on defense, but WR needs to be addressed in some form as bad as anything on the team.