Fair.
I read recently enough that Blizzard however, could easily get by on just the money they make off of whales. Their subs are not completely relevant in comparison.
...
CRPGs need subs the way RPGs need new blood and a constant influx of casual players.
Generally speaking it is the GM's that buy the product and do the work to run the game.
Is there some crossover? Of course there is. But again,
generally speaking the number of people that buy RPG product, and the number of people that play the game are two very different numbers.
But you do need those casual players to keep coming in to keep your game line going. And to keep the network effect of your game as big as possible.
It is a pure numbers game. For every X amount of casuals that start playing D&D a small number of them will go on to try out being a GM. And a smaller number of those will become the RPG hobbyists that will be the new 'old guard' in 20 years.
Which is good. RPG's need the hobbyist GM's as part of the the core player base the keeps the games network loop working.
Now for this:
So the question is, are the D&D Whales, that buy every book and whatever else, sufficient to keeping the train going forward, without the casual players as you define them?
Only if you want the game to die off in a few years. There are several RPG lines that have developed themselves into irrelevance by catering solely to their hardcore fans without thinking how a new player would approach their game.
People come and go in and out of RPG gaming all the time for various reasons. You want the new blood constantly coming in filtering through thousands of people to get that one person who will become the new Hobbyist.
So you need to keep your base more or less happy so that they are there as a readily available play network to help casual players try out your game.
It is a balance. In my opinion, WotC shifted the dial a bit too far to the 'player preferences' side of things; a.k.a. "D&D easy mode" and their retention after this current boom will not be what they think it should be.