As far as I am concerned, it is completely private what the two have spoken on the dinner.

Obviously Buffet knows very little about new technologies. And he doesn't need it. But I have also concerns about the long-term future of Bitcoin. Mostly because something even better can be invented. Maybe a much better system can be created. This technology is sooo young. We fly, but Zeppelins are obsolete. Something like that.
Or, the system can be hacked and ruined (quantum computers, somebody takes over 50 percent of the system, etc.)