I don't think unloading Smart for a draft pick really fits into that, given he's an upcoming free agent.
I mean, you can let him hit unrestricted free agency in a year with the knowledge that you don't intend for him to return, but that's a good way to make sure you get the worst version of Smart all this coming season, incentivized to hunt points and protect his body.
I also think throwing a 1 year $25m contract at Fournier can be a way to both maximise cap flexibility after next season while playing good ball next year. Not sure if he'd agree, but a showcase year here could earn him a Bertans-like contract next summer.
Fournier's in line to get something very similar to Bertans' $16ish million per already. Getting him to agree to a one-year deal at half or less of the guaranteed money he's in line to get over a three or four year deal is easier said than done. If we assume that Stevens gets him to agree to something in the realm of $25-27 million per on a 1+1 though (and I think he takes the 50-60 over 3 or 4 from someone else, for the record), you've shot most of your "useful veteran" tax budget doing that. Instead of flipping Thompson for another contributor, using one or more of the TPEs, and/or using the MLE you're in cost-cutting mode.
Given that the cap space route involves letting Smart, Fournier, and Horford go and handcuffs your ability to otherwise improve the team, I
highly doubt that it's the route the team chooses over the coming year. Maintaining trade flexibility with some mid-sized contracts attached to playable players offers a similar long-term upside while improving the team's immediate outlook.
Taking Beal for granted is an
excellent way to get outmaneuvered by GS/Philly/etc and poison your own locker room in the process.