If Emirates started Dubai flights, would they be able to use their signature A380 fleet to access Logan? [...] Is there sufficient market for that kind of traffic, but then again, when Airbus first came out with the A380 I thought it would be a dismal failure. It has since proven itself to have utility, so I suppose the traffic might warrant them if Jetblue fed the rest of the country to those flights.
The A380 has been a win for airlines and customers, but for Airbus it is a net-loser (like the Concorde and L1011s to think of historical great planes that were financial disasters to produce). It will be a long time before it pays back its development costs.
What type of aircraft would they likely use. I know an Emirates A380 got diverted here over the summer, but Logan could support that on the regular (physically and financially i assume). But do either of those airlines have any dreamliners coming in?
Emirates has A350s on order and won't be a 787 airline, and so far Turkish hasn't ordered the 787 either.
I can't answer the physical, but the financial answer is "No A380s".
I don't see how Boston can support an A380 financially to any market, and as evidence I offer how few 747s we currently see. The A380 gets introduced when one or more 744s prove too small (usually at a slot-constrained airport like Heathrow or Narita). We'd be seeing more than just summertime 747s to LHR/FRA/CDG if Boston were ready for A380s. As it is, BA/LH/AF have historically an additional 777/330/767-sized aircraft into a secondary connecting bank if they find they are maxing out their 747 service. (That secondary bank is either at a secondary time at their "main" hub, or at a "main" time at a secondary hub).
This is even truer now that BA needs to feed a scondary hub in Madrid, LH is running secondary hubs at Munich, Vienna, and Zurich, and Air France needs to keep hubs at Paris, AMS, and Rome all busy--and all of those hubs have more than one bank per day that can be fed. So the problem for any A380 operator is that there are competitors who would want to soak up an "extra" Boston travelers via their secondary hubs. From Boston, it is a 787 kinda world.
I think the safest assumption would be that Emirates would pioneer the route with the smallest aircraft they have with sufficient range. In the immortal words of Bob Crandall, "nobody ever went bankrupt flying aircraft that were too small." (as he sold off AA early 747s in favor of DC10s)
So I think (for Emirates) you'd be looking at either a B777 or a A330/340.