Sure, there are several other loops:
old-Masq/Rc or Prince could go on forever; Island/Dlands/etc. can create a setup where you have over 50% of the possible points, but cannot end the game.
new-Masq/Cpurse/Copper gaining (even just +buys)/bulk actions (two villages, Tr-variants, etc.) can steal the other guy's deck, but still lose to Islands and friends.
5x B-crat can stalemate on zero card hands. E.g. Prince x5, B-Crat x5 can stalemate with one guy having all the VP and the other having none and the former having no way to end the game. You will pile the silvers (and the coppers) ... but you can get trapped where you cannot afford to pile the curses for a third pile as everything stays in deck. If the scores are in the right places you can end up behind but leave the other guy no option to finish it.
With an obnoxious amount of setup, you can force a stalemate with enough plays of Pillage/Cr & Gov/Rogue & Grobber. Play a bunch of Cr/Gov. Get them up to a large amount of their deck (i.e. all of it if you want a true stalemate pin). Play Pillage until they have no functional cards left in hand (e.g. Curse, Estate, Prov, Copper) and then regain the Pillages for next turn. The get a hand that can buy nothing, but if they already 50% + 1 of the VP, you cannot end the game with a win.
Possession/Count or Mandarin can likewise setup pins.
Groundskeeper x5/E x2/Silver/Amb. You always can play Gkeeper until you have EESAmb; then play Amb (return E, give E to opponent); buy E. 5VP per turn is pretty good and with Amb you can pretty easily get there without a way to force game end. You can similarly get degenerate Whunt setups that make it too lucrative to keep at a stable state earning VP than to force game end. Pretty much ANY source of VP chips can become degenerate with limited draw options (e.g. Kc/Monument can by 9 VP/turn and even Kc/Crace can be too lucrative to actually pile anything.
