Upgrading the point guard is not Rockets' highest priority at this moment. What attracts them the most right now is a high-level power forward. In my opinion, JLin's position in current Rockets Team is pretty stable at least during the 2013~2014 season unless such a price as releasing him has to be paid as a part of the trading package for introducing an all-star level PF.
BTW, people around here often say that JLin is excluded in Rockets' long-term plan. Personally I don't see any solid evidence so far that strongly supports such a claim. Yes, I agree that by far Lin is obviously below the level required for earning a championship and the gap left for him may or may not be bridgeable. But, if he can keep the current momentum in improving himself, it's really difficult for us to predict what level he will be able to reach in the future 3~5 years.