It's thin ice. The annuity is untouchable except in bankruptcy, and even then it is backed by the PBGC.
The lump sum can stop two ways. A liquidity shortfall or pilot group votes to end it. Since near 50% have nearly nothing in it, and about a third have been totally hosed by b-scale, furlough, zero work rules except for FARs, it's thin ice.
It will be froozen as part of the joint contract and the pilot groups will fall all over themselves to sign on the dotted line. A large equity stake of the combined company will be the carrot. Dl/Nw got 6.9% of the company. I expect these guys will get around 5%.