Looking at the bigger picture, I'd say that would give the Maritime provinces populations like this (rough gut feel)
* PEI: approaching 2M, with 1M in Charlottetown.
* New Brunswick: 5-6M, with 3+M in the Tricities, but the north would probably have a million spread among the other cities. The north would probably be growing again in this situation.
* Nova Scotia: ~8M. Halifax would probably be 2-3M as the Maritime Alphadog, but Sydney is probably close to the 1M point, Cape Breton in total at 1.5-2M, and the rest scattered around Mainland NS.
So 15M in the Maritimes. That's almost inconceivable really.
Halifax would certainly have an NHL team, and Moncton and Halifax would have CFL teams. Moncton would probably be seriously considering an NHL team as well at that point.
HFR would be a thing between Moncton and Halifax, and probably between the New Brunswick Tri-cities. HSR might be in development for the Moncton/Halifax corridor, probably a Freddy-Moncton-Halifax corridor. Due to the empty space along the current TCH corridor, a HSR line between Freddy and Moncton would probably be easier to push through than a similar route between Moncton and SJ. (though that would be a nagging ToDo issue as well)
Route 7 would be twinned and probably 3 lanes each way between Freddy and SJ. Route 1 between SJ and Moncton would be 3 or 4 lanes as well, along with the rail routes. The direct Moncton to Freddy route might be upgraded in spots, but maybe not as much with the other routes available. It still goes through the middle of nowhere for most of its routing, but Grand Lake cottage country would make the Freddy side busier.
There would be a full 2-lane divided highway all the way up to Bathurst from Moncton.
Route-8 as I said before, would probably be mostly divided but likely still have some sections not done yet because the Moncton route exists. There would probably be more of a push to fully twin a route from Bathurst to Edmundston in this situation, probably by way of Route 17 and 11.
Route 10 to Minto and Chipman will probably be upgraded to highway standards (but not divided save maybe near Freddy). Those villages would probably grow to full sized towns of a few thousand people each; and shifting more to being more "cottage country" towns to serve tourists and vacationers to Grand lake from Freddy.
There would probably be talk of twinning Route 3 from St Stephen to Freddy, but the St John routing is probably enough for now; but it would likely be on long term plans.
Grand Falls, Woodstock, Sussex, St Stephen, Sackville would probably all be "small city" status, akin to Edmundston or Campbellton now. They're far enough away from the Big Cities to keep their identities for the most part so they should be able to grow to decent sizes before being considered part of another city's zone, like Shediac would have with Moncton.
Now that I look at it, I suspect that Sackville/Amherst will probably be a cross-border twin-city in this scenario.
Truro, Yarmouth, Bridgewater, Wolfville/Kentville, New Glasgow, Antigonish would probably be new cities in Nova Scotia of various sizes. Maybe Port Hawksbury as well, serving as the entrance to Cape Breton.