Depends on what's back there. You could remove the whole thing + the vertical lines and put in a large rectangular window to match what you see on the right. Otherwise, i think you have to follow the current lines, which means keeping the bay.

I do want to keep the bay, the question is am I able to replace it without having to replace the roof

Is the existing bay a factory built unit, or something that was custom constructed in place, perhaps original to the home?

Either way, you should be able to replace it while preserving the roof and skirt structure, however it will definitley require extra attention to the measuring and ordering of the unit as well as the installation obviously. Some companies won't touch it for that reason.

The other option that you alluded to would be to simply replace the individual windows within the bay. The viability of that option depends on how it was built along with the integrity of the existing "box".

Existing bay is a factory built unit, I communicated that I would like it replaced with another bay unit to my installer. Just didn’t trust the pocket replacement Idea as well as it would be the only window that would not be changed entirely. I’m doing the replacement with inline fiberglass windows.

In that case it will be a matter of whether or not Inline can produce the new window to the same exact dimensions, and the ability of your installer to make that happen if so.

What has he recommended? I agree that replacing the whole unit is ideal, however if the current box is in good shape and not sagging, replacing only the windows themselves isn't a horrible option. Most bay boxes are constructed and then windows are simply placed inside, so it may not need to be a "pocket install" per se, but potentially sized and installed the same as original.

One of the reasons I got concerned about the pocket install is because the window is being sized down 1.5 inches all around so I will lose glass space. So with that gonna definitely work with in-line to make sure they get the correct dimensions

Yes, that would generally describe most pocket installs, but since bays typcially consist of window frames slid into a pre-made box, you may be able to have those installed sized the same as original... It depends on the construction of the original bay unit.

I thought the same thing but the installer doesn’t seem to think he would be able to keep the sizing the same. So the safe bet for a win win situation is to change it as one unit and preserve the roof