They're already cleared ECS Shrewsbury to Birmingham for access to Tysley depot. The complicated bit on that route, and the bit where comparisons with 196s don't count for a whole lot, will be setting up ASDO and making sure the stopping points are ok. The 196s run with ASDO isolated, as all platforms on the route are at least 4 cars long. TfW will need ASDO to work.
There are plans in place and a date in the not too distant future when the work is hoped to be completed by.
The Cambrian will be a lot more complex, especially when the coast is included; lots of short platforms, level crossings at stations that need to be taken into account, plus the requirement to have ETCS working, and the need to train up nearly all ofthe crews. 3 out of 3 driver depots and 2 out of 3 guards depots that will sign Birmingham after the next TT change are all fully competent on 197s, but only a handful of instructors on the Cambrian do at present.