The repetitiveness of this forum is making it difficult to keep up but to pick up on a few things that's been discussed....
Capacity - There are currently only 16 3-car 175's in the fleet. There will be 26 3-c 197s. So some workings that are currently 2 car will likely be upgraded to 3 car. In fact the 26 3-car 197's almost completely replace the whole 2 & 3 car fleet of 27 175's. Secondly the proposed 5-car Swansea - Manchester services will likely take over the 3 car diagrams. And lastly, rather than looking at the capacity of each specific service, especially on the Marches route, people need to look at the overall daily capacity. With 2 hourly Cardiff - Liverpool being added there will likely be an overall increase in capacity even if the current formations on Manchester & Holyhead services are kept. With more options of services for people to choose from, this will spread out the demand.
ERTM's - It is likely that more than the original amount of 197's will now be fitted with ERTM's.
Cambrian capacity - If 4 cars can't work the coast, then i'm not entirely sure 3-cars can. It would be interesting to find out the exact reason why 4-cars can't and if 3 cars would be the same restriction. It would be good to see if extra services can be fitted in throughout the day, again to spread out the demand.
Capacity by type -
158 - 134 seats 0 tip up (Total 134) / 59 standing room
175-2 car - 118 seats 16 tip up (Total 134) / 58 standing room
175-3 car - 186 seats 20 tip up (Total 206) / 91 standing room
197-2 car - 116 seats 5 tip up (Total 121) / 79 standing room
197-3 car standard - 186 seats 8 tip up (Total 194) / 118 standing room
197-3 car with First - 158 standard 16 First 8 tip up (Total 182) / 120 standing room
So an overall drop in seating capacity of 12/13 seats by each type but more standing capacity, but likely an increase in capacity on those workings with First that will likely be 5 car for most if not all of the journey.