Personally, I think BYU is in a great spot. Yes the home schedule hasn't been good as of late, but the benefits of independence were always a long term play. As the years go on the number of quality P5 opponents will pick up, and the home schedule will improve with it. The 2021 schedule already looks good. in 2025 it will be even better. As the home schedule gets better the demand will pick up. Wait for us to have a solid string of sellouts and a season ticket waiting list before talking about expansion.
Fans make the experience much more than the stadium does. A prime example of this is when I went to visit some of my old mission companions in Mexico City. Someone had the bright idea to go to a Cruz Azul soccer game at the Estadio Azul. That stadium is a total piece of trash despite being located in a well off part of the city and the fact Cruz Azul is one of the biggest teams in Mexico. It only seats 33,000, and has next to no amenities. If I were white I probably would have been killed, but since I'm not it was one of the most amazing sporting experiences ever. The fans were crazy all game long and the noise was deafening. This wasn't even a big game against a prime opponent.
On the other hand, I've been to games at Sun Devil Stadium, which is a nice college stadium that has hosted a Super Bowl, that have been, shall we say, underwhelming. A third of the seats are empty, only the student section gets into the game, the energy just isn't there. These were games against USC, Stanford, Oregon, and UCLA, games that should be a big deal, and it felt like nobody cared. I would rather keep the capacity we have, fill it up, and have a great experience than expand at this point.