They don't do "share with a stranger" any more, happily.
How much cheaper it will be: I don't know. One of the problems I get as a wheelchair user is it is often impossible to tell how much the cost will be, because it is often the only classic room left and so they stop advertising classic prices. Always a complete mystery
With the MK3 stock as a wheelchair user you would be able to purchase a seat and be upgraded to the accessible berth (as there are no wheelchair spaces in the seated area, and subject to the accessible berth being available!) So the cost of a journey could be as low as £33 with a disabled Railcard. There being only two or three tiers to the seated fares.
Now on the Mk5 stock, as there's a wheelchair space in the seated area the cheapest someone can get into the accessible berth is £92, ok it's a loophole about to be closed but it also represents a fare that's over 3 times higher than previous.
Plus, as you are booking a 'room' now instead of a seat, the likelihood of using a Railcard to bring the fare under the carnet fare reduces!
What happens when the classic rooms are sold and only club ones are left, but the classic accessible berth still available, will I have to pay the club price for the classic accessible room?
Even using my Railcard I frequently find fares of over £160, a massive increase.
I'm lucky that I can tailor my travel plans to the cheaper days or times but the new fares now put even the cheaper options out of my budget!
That said, the sleeper is still my preferred option to travel to London, mobility issues prevent me using day trains and driving plus hotel ½ way takes too long, yet is fast becoming the cheaper option.