Second what Patricia is saying. Functional laundry is more important than a 3rd shower that has no real purpose where it is located

Value isn't just about square footage or number of bedrooms and bathrooms. Would have you paid less for the house when you bought it if it didn't have the third shower? if it were a 2 1/2 instead of a 3 bath home? If you wouldn't have paid more for the extra shower neither will anyone else.

All good points above.

The best thing though is to post a floorplan with dimensions of the area to see what would be optimal. From what you describe it sounds like you have made a valid analysis and a good decision to remove the shower so you have a better functioning space. IMPO, having 2-1/2 baths and a more functional laundry trumps 3 full baths.

It depends on the home as a whole. Post a layout. If that serves a guest room, then no.

Idk how wide your current space is, but what about pocket doors instead?

Does the third bath function as a powder room that just happens to have a shower or is there another reason for it? Pool bath? Shop or outdoor cleanup before entering the main house? Can't really think of any others, but those might be reasons why someone would pay more for a full bath in that location, but if it's functionally a powder room, a shower wouldn't seem to add any value at all -- functional laundry space will.