According to Stuart Sweet, Directv officially announced to dealers that 119 was going away. Dish doesn't gain anything by Directv dropping 110/119, from what I've been led to understand about the FCC licensing rules Directv just needs something up there occupying at least one of their licensed transponders in a slot to maintain control of them. They can leave the satellites at 110/119 in place until T16 launches and a new satellite is at 101, then move D8 from 101 to 119 to keep a hold on that. D8 has fuel life until 2034, that's a long time for Dish to wait. Not sure if Directv could easily hold 110, but its only three transponders so probably not worth them caring about.
Even if Directv abandoned these slots completely, it isn't clear how long they must be abandoned before the FCC would allow someone else to request use of them. Dish wouldn't be able to "put them to use immediately". I imagine Directv could do some delaying tactics to drag it out for years. At any rate, the satellite at 119 is licensed to mid 2021, and may well have fuel life after that. Directv just needs something to occupy one or more transponders...they don't need to have any customers receiving what is being broadcast.
I'm not sure whether Directv can actually transfer these licenses to Dish (when this sort of thing happened in the past where Directv picked up additional transponders they were buying a whole company) If it is possible, I'm sure AT&T would be willing to listen to Dish's offer though they could decide to only sell at a ridiculous price Dish wouldn't be willing to pay. If they can't actually sell them, they could have Dish pay for Directv to abandon them and immediately notify the FCC they want to terminate those transponder licenses to pave the way for Dish to get them more quickly (it wouldn't be guaranteed Dish would get them if someone else requested them, though that seems unlikely)
Currently Directv is using 1 4K channel per transponder. The plan as I understand it (from what Directv's former CTO said a few years ago) when they go to reverse band is they'll bond pairs of transponders and carry three channels - thus 54 channels on the 36 reverse band transponders. Others have claimed they will bond three transponders though I haven't seen any reference to that from Directv. It really doesn't matter though, it would probably be somewhere between 48 and 60 4K channels on those 36 transponders with a three transponder bonding.
IMHO there's very little chance there will ever be 48 4K channels, given that we are still at ZERO nearly three years after Directv was first able to deliver 4K. Directv is ready, but there is no HBO or ESPN or FS1 or NatGeo or any of the other channels people expected to see go 4K first - not only are they not there they haven't even announced any definite plans! The total number of channels will probably shrink quite a bit over the next 5-10 years, more people using VOD means having a lot of channels carrying the same stuff is unnecessary, so there will be HD bandwidth freed up over time if 4K ever starts catching on.