Will people really buy a Nikon d500 for $2500cdn, when that could easily have bought an FF camera?

It will depend on how good Nikon's marketing department is.

Yes, mostly for birder, sport, wildlife and anyone who need speed and more reach.

With very fast burst in full af and ae, low noise and high iso, it will be easy to take pic of bif, even with manual lenses.

If they didn't want a full frame, it would be stupid to buy one. Some people like the extra focal length.

Buy Cdn

There's a market gagging for it, apparently

$2500 is chickenfeed compared to the cost of full frame lenses.