The phrase "last bastion" refers to the final or only place where a particular idea, belief, or group can still be found or defended against opposition or change. Full definition
«The Senate is big money's last bastion of power, and it's up to Mr. Klein to demonstrate real leadership and get a bill to the floor.» (reinventalbany.org)
Democrats already control the Assembly and hold the offices of governor, comptroller and attorney general, leaving the Senate as the GOP's last bastion in Albany. (wxxinews.org)
As the apparent last bastion of the modular mobile movement, the Z2 Play is not only the flag - bearer for Moto Mods, but for modular phones as a whole in 2017 and beyond. (pocket-lint.com)