They could stand pat and keep the young guys but I think it'd be a disservice to the fan base and to Dame to not try to capitalize on the value of the young Simons and Sharpe. If Jimmy asks out of Miami I could see him wanting to go to Portland to pair up with Grant and Dame.
I don't think the price would be as high as many would think either. He's a top 20 player but with a massive contract and a ton of injury history. He's got a past that doesn't make GMs like him much and I think the Heat would allow him to choose his next destination. With all that said the Heat would still get a solid center to play with or behind Bam and 2 young guys to build around as well. A quick rebuild would be possible there.
The rest of the Blazers free agency should be built around finding veterans to play for the minimum and resigning current players. They have 2 picks in this draft and I'm assuming at least 1 would provide a rotational big that they can use but if not maybe they go get a defensive minded big for cheap (Biz) or trade Little for one (maybe Javale).
Getting Rose and Nunn provides some experience and previous teammates for Jimmy.
Resigning Cam and Thybulle gives them some offense and defense to mix and match their lineups as needed. It also tells both of them they are wanted in Portland which in itself should be a solid negotiation tactic to keep prices low.
Resigning Eubanks provides insurance in case they can't get production elsewhere.
Signing Trez came from the idea of them needing some energy off the bench. He is a poor defender but he can role and finish with some of the better backups in the league. He's also probably a minimum contract guy the rest of his career so that's nice. He could see this as an opportunity to get out of that by potentially winning the starting job which is a solid pitch for him.
I don't know what the taxpayer MLE will be or if Richardson would be willing to sign for it but a pitch of a starting job on a potential contender alongside 2 of the best players in the game could be enough to convince him to take a little less money then he'd make elsewhere. I went with 1 year as he may not be convinced enough to sign long term but then again he may want the long term deal to get bird rights.
Essentially a starting 4 of Dame, Richardson, Jimmy, and Grant would be great. The big man could be filled in by a lot of options on any given night. The bench would still have Little, Cam, Thybulle, Trez, Watford, Keon, Rose, and Nunn as well as 2 rookies who should be pretty solid.