I think borgein is right in thinking that Adobe will not really tackle the X-Trans issue before the next upgrade, i.e. LR 5.0. It just requires too many changes to fix it in an .update.
Why? Wasn't support for the X-Trans sensor added as an update already? It seems to me fixing it is a smaller update than adding it.
I can only quote borgein (who is a software professional) in full:
I was one of the first adopters of the X-Pro1.
When raw support was added to LR4.1 and everyone was disappointed about the results I was one of the first who said:
Proper raw support for the X-Trans sensor will not show up until the next major version of Lightroom (5.0) and Camera RAW (8.0).
The X-Trans sensor requires a major re-design of Camera RAW. The current support is "as good as it gets" within the capabilities of the current versions.
So to everyone that cries on every minor update (point releases): YOU WON'T SEE AN IMPROVEMENT UNTIL LR5 / ACR8 - NO MATTER WHAT. So stop hoping (and crying because it is annoying tbh).
[Posted today in the News section of this site, as a comment on the Lightroom 4.3 update. I for one am grateful for his explication, as to me it sounds very convincing. I think I now know when to expect this much wanted improvement, and when not to expect it. For the time being, case closed.]