I'm going to say straight off the bat, I think option 3 feels like the obvious choice. However, I'm going to play Devil's advocate here, after some thought I think there is reason for discussion.
A team would have to get $20.5 million below the cap to afford Dwight (assuming he’s not offering any discounts). If Houston lets go of most of their non-guaranteed or team option salary (Anderson, Brooks, Delfino, Garcia, Ohlbrecht, Smith), and they find a taker for Thomas Robinson with no salary coming back, then they’d have about $19.6 million in cap room (assuming a $58.5 million cap). I think they’d have to find a little more to trade, or convince Dwight he really wants to come there.
Throw Royce White into that T-Rob deal and the $19.6 million in cap room goes to $21.3 million. So after Dwight's signing we have a remainder of $700,000 which is unfortunately a little short of Greg Smith's $884,293 (assuming Dwight doesn't give a tiny discount).
Assuming these calculations are correct, it gives us reason to trade Asik. Not only will we be able to keep Smith, but assuming we don't take any salary back in the trade, we will also have over 8 million to offer another free agent.
2. We could have over 8 million to offer Paul Millsap. Paying MIllsap 8 million to play 30+ minutes makes more sense than paying Asik to play around 10 minutes (there will be games in the playoffs where Asik will play around 5 minutes). Paul Millsap made 6 out of 10 corner 3's this season, but because of sample size it's probably more significant that he made a 37 out of 72 (51%) of his corner long 2's. There is reason to believe Millsap could be a good corner 3 shooter if he just took a couple of steps back on all those long corner 2's.
Dwight--Millsap--Parsons--Harden--Lin would be an extremely strong starting 5.
3. We can get more chances to find another Chandler Parsons caliber 2nd round steal. The Blazers are looking for a defensive center because they need to make the playoffs and make Aldridge happy before he hits free agency, and they have 3 second round picks to give up in addition to a future 1st. I think this draft will be deeper than alot of people realize, with guys like Glen Rice Jr. and skilled centers like Mike Muscala projected in the second round. With 4 second round picks and Morey's genius, we have a good chance of finding another incredible bargain or four. Not to mention that future 1st rounder will be in a really good draft, if injuries strike the Blazers that pick could be better than expected.
To be clear, I'm only discussing the scenario that we trade Asik on the premise that Dwight verbally commits to Harden and Parsons. If that's not good enough, then we can wait till July 1st when Dwight is free to talk to Morey.