TOCs can't take on extra stock just because it becomes available. It will be 2022/23 anyway, too far away for most franchises.
2022/23 would mean that it would be quite some time after the start of EMT's (2-3 years) which wouldn't necessarily be ideal as you could probably get new trains just as quickly.
XC being a few months later could probably have similar thoughts, unless there was a good fit for them, but then I'd guess that in a similar timeframe they could get 222's from EMT so they wouldn't be of much help in showing lengthening of their Voyagers.
GWR are a better distance away as there's starts 8 months later in early 2020 (so 18-28 months). It's just could there be suitable routes to take all of them? (See above re numbers required for the Cardiff-Portsmouth services).
Next up is Thameslink et al. Where they could be used to replace the 171's at Southern, although the 3 coach units would need to be reformed in to 4 coach and 2 coach units to better suit the current mix of units.
Then it's Chiltern, which could use them. Although I'm not sure where, maybe as a replacement for the loco sets? (Puts on tin hat and ducks in advance of the backlash)
Next up are East Coast, TPE and SWR (all about the time that they'll be coming off lease) however they are all franchises that would justify buying new stock.
Then it's, about 18 months after the come spare, the start of Northern to start the next franchise. As such if they end up at Northern, chances are it would be part of the next franchise rather than this.