The DAA has gone out to several airlines and ET is not the only one to have been approached, just the first one that seems to have bitten.
The DAA would not have made these approaches if the govt were going to obstruct it - and the govt's policy is to encourage fifth freedom rights; the new aviation policy will enshrine this as policy - and a good thing too. If EI doesn't fly the route, it can't act as "dog in the manger". I can't see US carriers being too pushed, as no US carriers has sought to fly LAX-DUB.
There are still quite a few cities to which we don't yet have a link and I'm sure the govt would encourage the DAA to tout for routes and if fifth freedom rights work as the bait to reel them in, then let them do it.