Not delivering more than one DLC for the price of satisfying a relatively small player-base for is hardly "fair treatment", especially in the long run, when those stuck with old-gen eventually upgrade their PCs or consoles and have a chance of experiencing more story and (hopefully) quality content that way.
Is everyone treated equally? Yes. Thus by definition it is fair.
And they only have to buy the entire game again to do so. 
As unfair as it is to old-gen console users who have no plan to upgrade consoles ever, I have to agree with midnight_tea for the long run. In 3 years time would people still think that releasing just the one story DLC (JoH) for DAi because of old-gen limitations was a good decision? Well no-one can answer that until another 3 years has passed, so rhetorical question. I just think of it as this, for example, DAo having just one of it's DLC's after all this time had passed since it was released. So picture the only DLC they released for DAO was Shale's. Would people be happy if something avoidable had prevented them from releasing all the other available DLC's? we'll never know.
I hope the devs are able to do their best work this time, as DAI could some improvements lol, but the game and any future DLC isn;t going anywhere, you'd still be able to buy it in 4 years time.
I can answer those questions right now. Yes and yes.
Would people want more? Sure. But that want doesn't go away even if all the DLC planned are made since people will always want more.
You shouldn't have to buy a game again just to experience the content you got screwed over.
They didn't abandon anyone. Even the most diehard follower of old consoles will eventually upgrade to a newer gen system. BioWare's content is waiting and ready for that inevitable day, unless such people are just going to give up gaming completely once their old system dies.
I do agree it sucks that they stopped mid-game cycle with support and DLC, but they didn't set out to be "unfair" or screw people.
Abandon: to leave and never return to (something)
By definition, abandon is exactly what they did.
Not setting out to do something doesn't mean those things aren't done.
You mean. If you were abandoned, the others must also be abandoned. That's childish.
I'm on current gen, so I haven't been abandoned.