We could run out of space for sure. I'm also not 100% against moving a forward prospect (although I would hate to move Lambert, Yager, or Chibs at this point) for another piece, but IMO that return would need to be young with term as well like you mention. And that's only if you don't think Lambert can get there to be a 2C.
But we could also be in a position in the future where we aren't able to get Ehlers to sign, and maybe we lose both Names and Iafallo, and Appleton is offered too much for us to match in the offseason as well. And maybe Connor gets offered more than the Jets are willing to spend and/or wants a fresh start. Not saying any or all of this will happen, but it's possible we could see some significant roster changes as well and be happy to have the young players able to come in.
I guess my (current) ideal scenario is really just basically hoping that the "adding" we do at the TD is a even more improved Lambert (if he's at a stage that he could be an upgrade on Names). That way we're not moving another 1st or top prospect for a rental, and the guys like Lambert, Chibrikov, Lucius, and eventually Yager, Barlow, etc. are playing on their elc's to offset the increased contracts for Ehlers and Connor. We probably could really use another quality RHD prospect to go along with Salo too I think.