I have NO idea about any changes, but let me explain how the system was/is.
The stroller rental place at each park has two lines. One line is a payment line. People who pay get paper tickets (and a receipt). The other line is for actual stroller pick-up. When you pick-up a stroller, the CM at that line stamps your ticket with that day's date.
If you want a multi-day rental (it's NOT a length of stay rental, I'll explain that later), you go to the payment line. You tell them how many days' rental you want. It does NOT have to be for your length-of-stay, it does not need to match the number of days on your park ticket. You can have a 10-day ticket and buy two days of rentals, and you can have a 2-day ticket and buy 10 days of rentals. You park ticket is never part of the transaction -- the stroller CMs don;t know how many days you'll be in parks, but more to the point they don't care.
OK, so let's say you're staying for 7 days and decide to buy 7 days of rentals. You get in the payment line, tell them you want to buy 7 days of rentals. They will give you a strip of 7 tickets, perforated but attached. You then go to the stroller line. The CM will stamp ONE of your tickets. You get a stroller. Before you leave the park, you return the stroller and have the option of tearing off that ticket and getting in return one Disney Dollar. OR, if you're hopping to another park, you keep the ticket, and when you go to the next park you get right into the stroller line (NOT the payment line). They will see your tickey stamped with today's date and hand you a stroller. Also, you don't have to turn in the ticket on that day. You can do what I did and amass them and trade them in all at one time at the end of your stay and get one Disney Dollar for each ticket you hand in.
One thing I wish I knew when I was there -- UNUSED TICKETS ARE FULLY REFUNDABLE.
A previous poster said it perfectly. If multi-day rentals are no longer available, the big problem won't be the lack of a discount -- it'll be the pain in the neck of having to wait in the stroller payment line every time. There were times that that line was rather lengthy, and it felt great to totally avoid it. Please don't tell me they're taking away my stroller FastPass!!!