If we were back in the traditional franchising era, I could easily have seen voyagers being replaced in the next XC franchise. Many people forget that for the TOCs, the trains themselves are an Opex, not a Capex cost, as they are leased, and I can't imagine that they are the cheapest trains to lease. They must also be pretty expensive trains to operate, being heavy, thirsty and needing lots of crew for a fairly small number of passengers, and as they age maintenance costs are probably going up. Just as on EMR and Avanti, I could well see that a new TOC could easily provide new trains at a similar or even lower cost than the existing fleet, and also enjoy the benefit of a huge increase in capacity (342 seats in a 5 car TPE 802, vs 262 seats in a 5 car XC Voyager = 30% increase), even if the trains were to be a similar length. I could imagine there would also be the possibility for maintenance to be simplified, given that there are Hitachi depots in good locations for the XC services.
In this new world, it may be different, but I could still see the economics being similar - the DfT loses nothing if the voyagers all go to scrap - it is just the ROSCOs loss, but they gain quite a lot if they get new trains - potentially lower leasing costs, lower operating costs, reduced CO2, good messaging, ability to keep the Newton Aycliffe factory open a bit longer. The only difference now might be the capacity increase may be a bit less than in previous times.