If Labour are serious about bringing it all under one banner, then there are many cost savings to be had. Economies of merging train crew , plus not needing every individual TOC needing its own HR, PR, management, directors etc etc will all produce savings. In fact (and Aslef won't like this) but I can forsee fewer train drivers being employed and needed by allowing (say) a GWR Plymouth driver to be able to take a XC voyager from Plymouth Station to Laira depot, or further afield. Take out the ideology of "competition is the be all and end all" and suddenly money can be saved. Provided fares are regulated properly without competing franchises. It will certainly be interesting to hear more.....
Ps, anyone that mentions 1997, its ancient history and not worthy of comparison in 2023.