The only real hope for an extension, or for just allowing the credit to expire as designed, is if GM really has sunk millions into R&D and pre-production work on several more EVs. If they lean heavily on Congress, it might be as good as tossup odds. I'm inclined to believe, though, that GM is just making the right noises but isn't willing to do any heavy lifting. Likewise Nissan, who seem to be focused on their home market, with Europe to follow. They actually treated "Leaf 2" as a sort of compliance-like EV, by doing the minimum of upgrades to the existing platform. As long as they can sell some in the CARB states with hefty state tax credits or rebates, they won't really care if the US market grows, stays static or shrinks.
I just wish I knew for sure what is going to happen, as I have a specific Bolt in mind but would still prefer a 2018 Leaf...
2013 "Brilliant Silver" SV with Premium and no QC, a 2009 Vectrix VX-1 W/18 Leaf modules, and 3 EZIP E-bicycles.
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.