as far as I know from talking to several people who clearly know what they are taking about, the failure to upgrade the 777s was (1) unexpected problems with the Y upgrade and electrical problems, (2) when they got them sorted out they had issues arise with the contractor in China, and (3) they are very very concerned about cash burn and can't plop down the money now.

Everyone at UA is frustrated, they know its a problem, or better put a competitive asset that they hoped to have and don't have.