Well, that is the question. The only problem with Earth-2 is the way it has been managed, catastrophically managed, for its first two years it is one of the great successes of the 2011 restart with an average of 40'000 sales per month and an impressive world building exercise from James Robinson (and latterly Tom Taylor), and then comes 'Worlds End'... as a publisher DC threw this marvellous fresh concept into the grinder, all to make a quick bit of cash.
The idea of a lost JSA on Earth-1 intrigues me, and yet looking at the track record DC has in managing these things I am also hesitant.
I would think Earth-2 is not long for the schedules realistically, the book has been painted into a very tight corner in terms of potential directions and the sales are not good at all, so the new Rebirth JSA being hinted at is clearly being lined up as the replacement.
As I say, it has real potential. But then Earth-2 was a superb reimagining itself when launched just four/five years ago, so this depends on how optimistic you are that DC have learnd lessons in these last few years.
Think that the real Jsa coming back into the DCU would be great, as long as they have many of the prior members...
heck, the old/new Superman might in long run be better suited to being their team leader, rather than Jla!