I don't think this will threaten the project.
No one will try to fight the law. PSNH/laidlaw will simply revamp the language of the PPA, IMO, to the effect of, recs will be paid out until 2025. Hereafter, recs will be paid out within the scope of the law regarding recs until 2033. If recs are not extended past 2025, the agreement between laidlaw & PSNH at that point will........
It really is a simple fix if it becomes a stumbling block & I'm sure PSNH, being the lobbying power that they are, will be the major policy makers who have a say whether or not recs are extended past 2025. I'm sure if it serves their best interest, so shall it be written.
I' also think the PUC will appreciate the IPP's telling them that it's not in their power to accept the PPA, as is, lol.