It's a legitimate concern. As Vaz ages, his production will crater. Who will take his place? Wong isn't there. Plawecki doesn't seem to be the guy.
Other options on the farm:
Ronaldo Hernandez AA - hits the ball a ton (had a great July, but has been not great otherwise), but is a poor catcher
Kole Cottam AA - most likely an up and down 3rd Catcher role
Jaxx Groshans A+ - bat first, glove second guy
Jonathan Diaz A - tools to be an MLB guy, but is years and years away
Nathan Hickey FCL - similar to Hernandez and Groshans above, maybe moved off C to 1b or 3b
While there are more intriguing guys in the org today than a few years ago, it's a whole lot of question marks who really aren't going to be knocking on the door in 2022 and maybe not even in 2023. I wonder if they end up extending Vaz at some point.