I can't see how Morris is brought back at anything more than MLE type money. Just not enough minutes or dollars to go around. He is playing too well right now to trade him, but if he reverts back some, I still think there is a decent chance Morris gets traded at the deadline so Boston gets out of the tax this year.
I kinda' thought Morris might be traded before this season too, but now, even if he does revert, I can't see trading him when the Cs are trying to make a legit championship run. He's part of the rotation and a starter.
Morris seems to me like the type of guy that would take a discount to stay in Boston. He's been in Detroit, Houston, and Phoenix with coaches that don't really put him in a position to succeed. Houston traded him before the end of his rookie contract. Phoenix traded him after they signed he and his brother to value contracts. Detroit was a mess for a variety of reasons.
Now that he found a good situation on a good team with a good coach that uses his abilities well, I could see him signing a value contract to stay in Boston long-term.
If the Cs do make a big trade next year and empty the depth of their roster, I could also see the Cs signing Markieff to a good contract. Ainge wanted him a few years ago before he was traded to the Suns.
I think Ainge could offer a 4 year deal at the MLE to Marcus and a shorter deal at the tax-payer mid-level (5-6 million) to Markieff.
However, if the Cs don't make a big trade, there just isn't much room for either.
He is in the rotation, but ideally he is the 7th or 8th man on the team. Still valuable, but not so valuable he can't be moved especially in the playoffs when the minutes increase and the rotation shrinks. I can even see a scenario where Morris barely plays in certain playoff series (the ones where Baynes is needed more). That is also true of Rozier and given both of them are expiring contracts who have a very good chance of not returning, I wouldn't be surprised at all if either or both of them are moved for longer term pieces.
Ideally the playoff rotation will be something like this
PG - Irving 38, Smart 10
SG - Smart 20, Brown 28
SF - Hayward 38, Brown 5, Tatum 5
PF - Tatum 33, Horford 5, Morris 10
C - Horford 33, Baynes 15
Or something in that range. I really don't see the need for Rozier to play at all in the playoffs (other than foul trouble or blowouts). Against some teams Morris will get more minutes than Baynes and against other teams Baynes gets more than Morris.
So given that, I'd absolutely trade Rozier, and if the right trade came along for Morris, I'd move him without giving it much thought, especially if the trade dropped Boston below the tax this season (which I still think has a very real possibility of happening and being a goal). The team is so close to not paying the tax, it would be a shame to start the tax clock ticking when some minor moves can get the team out from under it.