If (when) FLEX is deemed a failure, I highly doubt that they'd go for Stadler Bi-modes. I think I've explained my logic before but I'll do it again anyway
The 769s weren't procured for their bi-modal capability but because they were supposed to be in service fairly quickly and could move under their own power - the fact that they were bi-modal was a pleasant coincidence which will have influenced what routes they went on, but fundamentally it wasn't important. (much like Wales)
Northern need the extra capacity these will bring yesterday and Stadler seem to have a relatively long lead time compared to CAF. There is also the fleet commonality points as well, and for a franchise that is supposedly an economic basket case, any savings that can be made through standardising the fleet should be taken advantage of.
195s working long distances under the wires would most likely be politically unacceptable.
I'm not convinced that it would, otherwise the 195s and the subsequent CAF DMU orders for Wales and the West Midlands would have been forced to be bi-modes from the start.
I suspect that the people of the North want new trains and additional capacity, whether it runs under the wires without using them is of little interest to them, and it's not as if the recent electrification projects will suddenly be unused either. Don't forget that the 769s would have been replaced on Windermere services by 195s in the long run anyway.