Franchise-altering means one or more of the following players... Pastrnak, McAvoy or Marchand.
I'm not counting Bergeron and Krejci, as they're likely already gone.
Pasta has a full NMC
Machand has a Modified-NTC 6 team trade list, that has turned/or turns into a 15 team no-trade list very soon.
McAvoy has no trade restrictions, but D like him simply don't grow on trees.
Maybe Dom can confirm Marchand's M-NTC change date.
Of those three, I think Marchand is the one that kind of fits the re-tool bill.
He'd get a solid haul of now/futures etc, as he is still impactful and a steal of a contract.
Pastrnak's NMC kicks in July 1st I believe.
Although, even though I don't even think it's likely, to happen, mentioning it hypothetically will probably cause some sort of reality police to come forth and scold anyone for even mentioning the possibility.
McAvoy, I can't see them moving him unless they have an answer on replacing him, top pair D are even harder to replace than top line wingers. (both are not easy to replace either)
Lastly, the "Franchise-altering" comment was made by a non-verified source,, (and more or less mocked by another tweet), so while not impossible a big move happens, take it with a grain of salt.
That said, I'm still in the mindset anything can happen. Whether realistic or not, I'm here with popcorn.