There seems to be a lot of rumours floating around on CJDBY that a second 003 is on the books and in fact construction may already be under way at Jiangnan Shipyard. Some say there are modules at Jiangnan that looks like they could be pieces of another 003 hull but I don't have a CJDBY account to see the photos for myself, anyone?
Here's a fresh thread on this topic just today:
I also read this piece last week that hinted at the same thing, although I don't think that's all that strong of a statement:
Within the next five years the PLAN will likely accept in excess of ten new large warships into service, including two more aircraft carriers, 3 LPDs, 3 LHAs (landing helicopter areas), and six Type 055 destroyers.
Six 055 would run against POP3's claim that 14th Five Year Plan calls for building of 8 new 055, and AFAIK also 5 additional 075 instead of 3 claimed here. So take it with a grain of salt.
That said there doesn't seem to be any visible movement on 004 aside from expansion of facilities at Dalian. So if there were plan to build two carriers ASAP (given geopolitics at the moment) than another 003 would make sense. It would also fit with PLAN tradition of building new design a pair at a time. What do we think?