Odds are they won't. Getting more PS1 classics onto the store is not a high priority.
And if the games are not developed by them, then there's that. They'd have to get permission from the developer to make a digital classic, then re-code the game to work, test it to ensure compatibility checks out and that there's no security loopholes.
It's a costly process, they have to decide whether its profitable.
I see, I wrote some good reasons why they should make these games alvailable in page 1. I think it will be profitable also, but it will also be meaningful to sony fans I think. Sony had some really good games when they first started making games. I think it would be good if they were brought back, so we can enjoy them again, and learn about them.