After the TYL, everyone has the memories of what happened, thanks to Uni. She made it so that everyone would know what was going on. This means that Xanxus knows exactly what his future self did. With that in mind, there is one small thing worth mentioning. The Shinmon or Inheritance Arc is important for one reason as far as Xanxus is concerned. As long as Sawada is recognized as the tenth boss, you can expect that he'll do his work but that he is not required to interact or support the kid in any way, shape, or form. He will continue to serve the Ninth (and no one will question why). While Tsuna goes to this ceremony he meets the Varia. Only, Xanxus isn't there. Squalo promptly tells them that there's no way Xanxus would show up to this kind of thing with Sawada present. Despite Tsuna relying on Xanxus in the TYL arc, Xanxus is still the selfish and immature bastard he always is.
Sawada's there, not going. He's so selfish and stubborn that he merely sends his men as the representative of the Varia. Although, I have always believed that if there was going to be a representative of the varia, it should be the boss. Xanxus, I'm looking at you. Now, I wanted to highlight this for one reason. He is still so self-centered and his own loathing of Sawada is still enough to cause him to avoid Vongola functions despite his desire for the family to be strong. Basically, Tsuna has to deal with Tsuna problems.
On the other hand, this is still Xanxus giving Tsuna the finger and saying, "Get out of my face, trash." I'm not sure he could make it any more apparent that he does not support Sawada as the tenth generation boss. I like to think of it this way, just because he came to a sort of understanding in ten years, he's not there yet. And though he may be one day, he will never openly admit it to anyone. That's part of his pride.