Hard to really pin it down, but a rough guess is that you're going to lose what looks to be at least 1/32" off the edge-side of the blade. After that you may be ok.
That's a wild guess - it's impossible to say accurately until you cut into the steel. Pitting is evil - it hides and runs on the inside sometimes.
The outside can look like carp and it'll hone out quickly and easily.
Other times - it's so invasive that it's not worth honing out.
I've honed out way worse-looking blades that that and they were fine when done.
Spine wear will increase - taping first before clearing the pitting can help minimize that.
I don't do use tape for that usually, but it's a common practice.
Pitting like that it's a 50/50 type of situation. You can end-up with a shave ready razor that will hone very easily or you can end-up with a razor that will always chip (or micro-chip) on that spot. I had such a razor and it would take an edge for a while. Eventually, I would re-hone it and it would take a while before the edge would be to my liking. I finally trashed it as I was getting tired of honing it for hours so the edge would be perfect where my other razors were taking the edge very easily.
In any cases, if you practice on it, you can learn quite a bit out of that one.