Was the continuation of Tsubasa Reservoir Chronicle ending in manga shown in Kobato?
In episode 20 of Kobato, when Kobato mentions that Syaoran and his companions have been traveling for a long time and Syaoran says,


   "but it's a not journey with a destination. I guess you could say our destination is to continue travelling." When Kobato asks if it's undecided where they are going, he replies, "It would be difficult to decide. For one thing, we don't know how long we can stay in one place. But, I have someone waiting for me."


So it's definitely after the end of the Tsubasa Reservoir Chronicle epilogue published in October 2009, (Episode 20 of Kobato aired in March 2010):


   Syaoran is on his journey and they've been doing this for some considerable amount of time.  Where Syaoran went to look for a world where the clones can live, Sakura stayed in Clow because of her dream that she'd only cause sadness if she went with Syaoran, thus she is the one "waiting for me".


As far as I know, the October 7th epilogue was the last of the story, as a way to sort of tie up the loose ends. Kobato's crossover generated a lot of speculation about maybe getting more Tsubasa out of CLAMP, but they announced in 2009 that the epilogue will be the end. There hasn't been any official news about the manga or continuing the story since. Though it wouldn't be surprising to see more crossovers with Syaoran, Fye, and Kurogane continuing their journey in future CLAMP productions.