Currently 319427 is being looked at to see if its possible. Another 3 units will be done if it proves successful for use on the Windermere branch, however it seems the word has reached the lne user group and they aren't happy at the idea.
Could an enhanced service be considered by converting a larger number of units? That would surely be popular.
Using all Class 319 bi-modes, you could run a two-hourly Manchester Airport-Lancaster (split)-Barrow and Windermere service, and then an interspersing shuttle to take both lines to an hourly fully-clockface service. Get it all nice and clockface, and more through services and more capacity (8-car running on the busy bit). Everyone wins.
Replace the seats with some good quality 2+2 InterCity-style ones with generous spacing (6 rows in each section rather than 7 with mixed airline and table) and potentially fit aircon (think Renatus) and there's potentially a very good unit indeed, much better than the ageing 2-car DMUs (or worse, pairs of dirty, run-down 153s that appear to infest the Furness line at present) that are otherwise likely to be used.
You could, as the units would be dedicated, introduce some strong "Lakes and Furness" branding to help promote the services.
But I guess the user groups would rather stamp their feet and scream "we want 185s", despite these being (a) rattly, noisy DMUs and (b) too short with an incredibly inefficient interior, and so having them resigns both lines to the present overcrowding issues continuing.
FWIW, I know cost is an issue, but if Windermere electrification were to be permanently off the agenda might an add-on to Abellio's Stadler bi-mode order be worth considering, again for both lines? They are an absolutely perfect fit for a bi-mode capable of 100/110mph on electricity and 60-70mph on diesel.