I don't have a timeline. We have been to WDW once a year for the last 7 years (one year we went twice). We have been and tried
MDE/FP+ last fall and we hated it. We definitely felt like we got less done, had more hassle, and that it took some of the fun out of our trip, although it is Disney and we did still have a great time- just not as great a time as usual. There was way too much being tied to a phone with a glitchy app and time wasting and having to criss-cross the park by FP+. You have to book 60 days out to FP+ attractions you don't even know will have lines that will need FP+ on the day you are there at the time you want to ride, and also when you don't know what part of the park you will be in at the time your FP+ kicks in (we know our schedule pretty well, and we had trouble and had a lot of criss-crossing- I can't imagine what it is like for newbies). Changing a FP+ to something you do need was about impossible on the glitchy app when we were there, and I imagine now that FP+ has opened up to eveyone, it is pretty much impossible whether or not the app glitches.
We usually take 2 Disney trips a year, one to WDW and one to DL. This is the first time I have not had anything booked for fall or the holiday season at WDW by this time in the last 7 years. If nothing about FP+ changes, we will probably stick to DL for a while. Assuming nothing about MDE/FP+ changes, which I am optimistic it will, we will probably return to WDW when we miss EPCOT WS enough that we are willing to deal with MDE/FP+ again just to get our EPCOT fix (The lure of riding the mine train once might also get me back, depending on what gets said about it when it is finished and operating. But-it would have to be on FP+, and if we could not get a FP+ for it when our 60 days arrived, then I would likely cancel the trip). When we are at DL, really EPCOT is the only thing we miss. Well that and the fact that for DL on-property resorts it usually costs us the same for 4 nights as it does to do WDW for 7 or 8 nights. I was thinking about going ahead and booking a WDW trip for late this year and getting ADRs in place, in case things change by then, and if not, then I would cancel the trip and we would either do a 2nd DL trip, or more likely do a non-Disney trip like maybe NYC. We are planning on skipping WDW this year if things don't change. We may very well skip next year too. Beyond that, I don't know if the EPCOT pull will be too much, or if we will get so used to trying other places, that it could be 4-5 years before we go back to WDW. I don't see us going more than 5 years without WDW- I don't think I've ever done more than that since I was 7 years old-but you never know.