But your question still applies to recoverable flight plans. How many do they need to cover all those?
There are launches which don't have enough margin to land at all. The upcoming EchoStar 23 launch is one of these. This is a GTO launch of a really heavy satellite, so getting it up there requires using the fuel the rocket would need to land.
However, this is rare, and it's likely that this will only happen a few more times at most
Especially once Falcon Heavy comes online.
If your payload and destination allow for reuse then the cost of your launch is (cost of the whole rocket) / (number of reuses) + (landing & refurbishing costs)
If you require the full fuel of a Falcon 9 it might make sense to accept higher risk and launch on a rocket that is at it's last launch.
If you also don't want that risk, then maybe a mid-life Falcon Heavy can be cheap enough for you.
If Falcon Heavy is still too expensive even with re-use then maybe a one shot Falcon 9 is right for you.
The Block 5 upgrade will bring the performance of Falcon 9 (in a recoverable configuration) up to the point where flights like Echostar will be able to make downrange barge landings. Heavier payloads (which are _very_ rare nowadays) will fly on Falcon Heavy.
Polar orbits are almost always low-earth orbits, and therefore are much easier to recover. I would be very surprised if they ever flew an expendable launch out of Vandy in the future.
Yes, but how much of that is because there isn't anything to launch them? When Falcon Heavy is up and running, a commercially feasible option will exist for the first time. Maybe that'll change, and we'll start seeing things in space that weren't commercially feasible before.
They have to fly expendable now, because customers can just fly on Ariane/Atlas/etc if SpaceX said no. Once Falcon Heavy is flying, there won't be any competitors with the same payload capacity (until New Glenn, which is also planning first stage reuse, but is still very much a paper rocket at this point).
However, they can build that into the cost of the lift. If the rocket isn't recoverable because of what they want to put in it, just charge them for the rocket.
Either way it is better than what we have now.
/me looks sternly at DooM