I think it's just that someone has to go if we sign Stone and somehow we need to replace Trouba if he won't sign long term. We have an embarassment of riches on the wing but, Wheeler has a NMC, Stone would have just signed, given the contract given out to Nylander Ehlers contract looks like a value deal, which means either Laine or Connor could be moved for that Trouba replacement. We have teams like Carolina that are on the record trying to move a RHD for forwards...
IMO if Stone signed long term you'd need to look at the asks for both players and shop them both to see what the returns looked like as one of them would need to go as a cap casualty. It's really hard to fathom trading Laine when his ceiling is a 6 foot 5 goal scoring machine. Nobody has accomplished what he has at his age so people speculate about Connor. Ehlers looks arguably better in his spot on the top line than he does and is only 1 year older.
I don't think anyone wants to trade Connor, but looking at the numbers we may be forced to trade a top 6 winger to make the cap work. Maybe it's Laine? Maybe it's Ehlers? Maybe it's Connor? Maybe we keep them all and don't sign Stone? The last one is probably most realistic but not as fun creating trade scenarios.