Tippett is 23, and he's starting to look like the high draft pick he was. What are you going to trade him for, a late 1st rd pick that might become another Tippett in 5 years? That's the most you'll get.
You trade young players who aren't good fits, that's it, otherwise you build around them, in three years you can always move them toward the end of their contracts for NHL ready prospects and some draft picks thrown in.
It shouldn't take a decade to rebuild, unless you're Buffalo or New Jersey.
Flyers have a good young core, what they lack are elite players, Gauthier #5, 2023 #5?, 2024, maybe someone takes a step up (Brink?).
Gauthier, draft pick, TK, Farabee, N Cates, Frost, Foerster, Tippett, Brink/Allison/Lycksell - that's your top nine in two years?
Cap space is only a thing if they want to waste money in free agency, otherwise they've locked up their starters and it'll be years until they have to pay their younger prospects.