I think they will hold 1914 for awhile longer but eventually it will cease to be of any importance. It's already so long ago to most younger ones that it might as well be 1799. But, eventually they will have to update the date. I don't know how but I am sure they are working on it.
I also think the overlapping generation teaching won't be around a long time. I think that whole thing is part of a two step plan. Step 1, overlapping generations. Step 2, generation just means common collective memory regardless of when you were born, they could say that theoretically this type of generation could last for hundreds of years since modern technology keeps our memories much sharper than they would be generations ago. See, our kind God gave us modern technology in this time of the end to ensure the generation spoken of could be long enough to see the events of 1914 or XX date and the end of the system of things whenever it happens.
just my idea.