There is, however, one potential problem for the show’s future. “The big issue is that I have only written three novellas, and I have a lot more stories about Dunk and Egg in my fucking head,” Martin says, looking a bit shamefaced. “I’ve got to get them down on paper. I began writing two at various points in the past year. One is set in Winterfell and one set in the Riverlands …”

There aren't least two additional problems.

The first is actors ageing out of their roles. The actor who plays Egg is 11(ish?) and assuming the rumor is true and they shoot the next two novellas back to back, he's still going to quickly age out of the role.

Maybe the later stories take place with an older Egg, certainly there are plenty of stories to tell about an older Dunk and Egg. We know the adventure ends at Summerhall, and while the details are missing, the general idea could be written by any competent writer. The only catch is if Martin has some specific magic he wants to add.

The second problem however, and it's highlighted more by the later part of the interview, is that the Dunk and Egg stories aren't the meat of the story. They're an appetizer. They exist as a fun little series of tales between the main stories. The interview highlights that George isn't confident in season 3 of House of the Dragon. Season 1 was excellent and Season 2 was mostly good, but ended abruptly. It gave similar vibes to Game of Thrones season 7. "It's ok, I can forgive a lot as long as next season fixes it."

If there is no main course "Game of Thrones" or "House of the Dragon" show... I don't see Dunk and Egg getting the ability to continue. There is plenty of mythos to pull from, but they need to find someone who can actually turn it into a TV show.