The translator application is publicly available, and you can look at the actual data just the same way I can, rather than filling the boards with meaningless speculation.
Here are the facts: the translator will be 250 watts, 41 meters above ground level, from a tower on Wharf St. in Weymouth. It will indeed be directional, but only mildly, with a notch to the south-southwest that will protect the 101.1 translator for WATD(AM), and a shallower minimum to the northwest protecting WGIR-FM and, coincidentally, avoiding wasting RF over the harbor. It will put 60 dBu over most of Quincy and Braintree, all of Weymouth and Hingham and most of Hull.
The red contour here shows what this signal will look like:
https://fccdata.org/?facid=202403
There's really no "if" about whether this translator will materialize. Ed (and Dennis) have followed the FCC's process to the letter. Their application will be granted within the next few weeks (maybe even sooner, if the Prometheus translator objection is swept away promptly.
Now we move from fact into (well-informed) speculation:
In 2018, there's little value to a daytime-only AM signal, and huge expense involved in building up a higher-powered full-time AM signal. Ed's a good businessman, but he doesn't have unlimited resources. He spent $125,000 on the WMEX license, plus, presumably, legal costs that will be involved in defending against the transmitter site lawsuit. Is there a business case that would justify dropping another $100,000 on a high-powered AM installation that could do 10 kW or more by day? Or half a million or more (maybe much more) on the new directional installation that would be needed to get any significant night power?
I can't see Ed doing that. What makes more sense, I think, is that 1510 basically ends up being a minimal signal - not much more than the kilowatt daytimer in the STA - just enough to serve as a primary for the translator. And I don't think it's coincidental that the WATD(AM) translator is also on 101.1.
I think Ed's game here is going to be to simulcast the 101.1 translators. I think the AMs are there only because they're needed as nominal primary signals. And if I were a betting man, I'd make a wager that both of those 101.1 translators will be used to extend the reach of WATD-FM's programming to the west and north of its current core signal. I may not be as smart a broadcaster as Ed, but that's the move that would make the most business sense to me if they were my stations.