I assume that if I use any of the new P2SH-based addresses in Armory, I no longer have that option; i.e. I can get my private keys out of Armory but I cannot make the corresponding scripts in another wallet, and therefore cannot (easily) spend the funds.
The P2SH-P2PK script is most likely unique to Armory. The P2SH-P2WPKH one is actually "standard" as it appears in the original BIP as one of the script types required for SegWit support. Other wallets out to provide that.
EDIT: I don't think the risk is vanishing. If goatpig had not picked it up, Armory development would have stopped after etotheipi stopped working on the open source version. And at least once did the Bitcoin network implement a soft fork that required an Armory update before it could sign transactions again.
1) Someone could just as easily look at the code and make it spit all script variations if support disappears.
2) If the wallet you are using stop being developed, do yourself a favor and move your coins out before the most recent version turns obsolete.
3) Eventually there will be someone who'll figure there's demand for wallet interchangeability and will write an offline tool.