I'd do some version of this trade in a heartbeat. Though I'd prefer a top prospect and a 2022 1st personally. At the end of this season Helm, Glendening, Bertuzzi, Hronek, Filppula, Ryan, Gagner, Erne, Staal, Nemeth, Biega, Merrell, Weiss, and Bernier come off the books. That's roughly 46 million dollars in cap space accoring to CapFriendly. Bert, Hronek, and maybe Glendening and Bernier will get new contracts with marginal raises, totally no more than 10 million over and above their collective current cap hits. Killorn and Johnson are another 9 million. You've still got about 27 million dollars to round out the roster, and most of that will come from guys like Ras, Seider, Zadina, Veleno etc. who are all on ELC's. PLUS Killorn and (to a lesser extent) Johnson are actually good, so you can maybe flip them toward the ends of their deals.
Of course you do this if you're getting another 1st and a top prospect. It's a steal. You'd have all the cap flexibility you'd need. You could do everything described above AND sign a top free agent or two. Plus the following year Dekeyser, Nielsen, Namestnikov, and Stecher are UFAs. The first two are unlikely to be brought back and the last two, if brought back, will only get marginal raises.