Hello,
dont know how to explain, but if Young Justice comes to Earth, Doomsday Clock ends etc. there will sureley be a lot of explaining needed.

What do you think will be the consequences?

I mean we saw what happened with Wally...

Now:

there could be a problem with Superman if Conner comes back and Superman finds out that Martha and Jonathan didnt die so early...
Problem with Barry Allen, because he is to a certain degree responsable for all this
Roy (if he comes back),Ollie,Black Canary,Starfire,Nightwing and Donna will be upset if they remember Lian, who wasnt born in NEW52 and Rebirth
etc, etc,

What do you see in the future, because connecting NEW52/Rebirth with Pre-Flashpoint will create trouble and create anger,desperation etc. among the Heroes...