I expect these will be kept green for the main network routes. At current service levels, the 27, 81 and 91 need a total of 12 vehicles I think (roughly, give or take), OTB said that the 17/18/19 will interwork with a total PVR of 5 double decks, so that takes the network PVR to 17, just 2 below the number of green MMCs.
In terms of the Tinners, the current T1/T2 need around 15 vehicles (again, roughly give or take). When the remaining reds return, they could be used on the college T3 service (with college route interworks) as that would fit the brand.
I guess that the MMCs first in line for the paintshop will be the U-Lines branded ones (along with the blue E400s and the vehicles for the Lizard network), as OTB has said that the U routes will be joining other brands, suggesting that U-Lines is no more.
Note that all of this is completely guesswork from an enthusiast with no factual knowledge of plans so is likely very wrong.