How many Popes' portraits can fit on the walls of the Basilica of St. Paul Outside the Walls?

I was watching a video series on the Rosary at a men's group this morning and they were talking about all the popes on the walls at the [Basilica of St. Paul Outside the Walls](https://en.wikipedia.org/wiki/Basilica_of_Saint_Paul_Outside_the_Walls) and it was mentioned that it was super cool that all the Popes were on the walls - I think the portraits of the Popes roughly matches what is [on the scrollbar of the vatican.va site](https://christianity.stackexchange.com/q/86360/10672) . What I'm wondering (and this is not wholly idle speculation because maybe when they run out of space we'll be at the last Pope and that'll mark the eschaton) is how many spaces do they have left and is there a plan for where they'd put popes if they do run out of space? I've never been there before so maybe I'm off base and there are choirs of popes and they won't have a problem for 3000 years, but I think the question can still be answered either way.