FWIW, I've contacted Disney three times with this question, and gotten three different answers. Specifically, I was asking: When I booked Garden View at YC, those rooms included Admiral Pool (quiet pool)-view rooms, and we planned to request one. Now that the categories have changed and some rooms have been switched to a different category (e.g., most or all former Standard View rooms are now considered Resort View, and many Garden View rooms, including ALL of the quiet-pool-facing rooms -- half of the entire Garden View inventory! -- were changed to Water View), can I still make that request without being told, "sorry, that's a different category?"
CM #1 told me that Disney's system has automatically converted my Garden View reservation to a Resort View one, and that since that's all the room assigner will see from their end, I can't request an Admiral Pool-facing room because that's no longer available in my category. What's more, they said that I could very well be assigned a roof or parking lot (Standard) view, since those have now been added to Resort View.
CM#2 told me that because I'd been "grandfathered in" by booking a Garden View room before the categories and designations were changed, I was 100% guaranteed to get a room that was considered Garden View at the time of booking (and not any of the Standard Rooms that have since been reclassified as Resort View), and could therefore request an Admiral Pool-facing room, because those were included in Garden View when I booked.
CM#3 put me on hold so that she could consult with a higher-up in Guest Services. She returned to tell me that even the supervisor with whom she spoke said that Guest Services "still has no idea how this is going to work" from the standpoint of room assignments, that she couldn't answer my question, that anyone else who'd given me an answer had to have been "just guessing," and that the supervisor had suggested that I call back later in the summer "after the details are hammered out."
My attempts to get a straight answer from Disney may have failed, but my position is: if you booked Garden View CL, go on the touringplans room finder tool (which hasn't been updated to show the new room categories and changed designations yet) and screenshot where the Garden View CL rooms (and Standard CL rooms) were, so you'll know for future reference. Make your room request as planned. If you don't get it, and the front desk tries to tell you they couldn't satisfy your request because you're requesting a different category, OR if they assign you a room that was a "Standard View" at the time of booking, push back. Politely demand to be placed in an actual Garden View CL room (as they were designated at the time you booked), OR to be refunded the difference in cost between a Standard and Garden View at the time you booked. For Disney to sell you one view category and then downgrade or diminish it before you arrive to something else, without compensation, is fraud.