Well the government scrapping several electrification projects in favour of using bi-modes is one of the reasons 769s are being widely-ordered.
The uncomfortable truth is that at the glacial speed of delivery of the electrification schemes currently under construction we need to cover at least 10 more years before whole lines can be connected. Ideally what should be happening is that lots of infill sections should be being tackled so the 769s can cover until completed.
Oxenholme - Windermere is the most obvious in the north, but Leeds - York would be good. Midland Mainline is likely to be more time consuming with the need for a lot of infrastructure rebuilding, not least at Leicester and Sheffield.
In the meantime bi-modes let us use some electrified tracks. Maybe after Brexit the new government might loosen the purse strings for a rolling programme of electrification, spurred by the nonsense of trains running only part way* as electric.
A momentum of opinion is growing that these units, even if completed, are likely to be deployed elsewhere. Part of their business case was compatibility with 319s, yet there is doubt about their retention. I've tried to remain open minded on this, and to believe they will come into service. The lack of more than two delivered units, the lack of any route training, and their current expulsion to Wabtec, begins to look like a washing of hands. Out of sight, out of mind!
If that's not the case we need to see some specific evidence to the contrary very soon - say by the end of July - or reluctantly I'll be coming down on the side of all those called Thomas with doubts, those doubts increasingly confirmed by every extra day when no trains run on customer served tracks.
* The rail link from Madrid to El Ferrol via Santiago is not only bi-mode on traction, but bi-gauge on the tracks. Apart from when it was taken round a bend at twice the permitted limit, it does very well. And it's saving a lot of fumes on the section from Madrid to Santiago.