I think they will just phase out 1914.
As we've seen with all the date changes in WT history, in practice no date (including 1914) is crucial for most JWs: "My service to Jehovah isn't tied to a date."
IMO, for most JWs, the only things that can't be changed by the Society without losing them are:
1. The name "Jehovah"
2. The kingdom and paradise earth promise
3. No trinity
4. No war
5. No hellfire
Changing the blood doctrine would cause many who have lost loved ones to leave, but most JWs would be fine with the "new light."
The hyping of various dates for Armageddon has always boosted meeting attendance, field service, and numbers.
Without something new to fan the flames, many long-time JWs get weary, disheartened, and even disillusioned by the never-arriving, vague claims of the imminence of Armageddon.
Many fall away, but they are replaced by new dubs who haven't experienced all the apocalyptic letdowns.
Most weary old-timers stick with the organization because they have invested too much of the lives in it to admit to themselves that it's bunk.
They gut it out because they have nowhere else to go where they can find the "Big 5" above and because of fear that they will blow it all if they quit now because Jehovah is testing them and because of the mantra that "he who endures to the end will be saved."