Splinterlands is going to be fine in the long run because it is a game offering real value. The thing that makes me nervous about SPS is that it is divorced from the game.
In-game currencies that are vital to playing a game are the ones that will thrive. I'm not sure how SPS will fair in the long run due to the fact that you can play Splinterlands for your whole life and never once have a need to touch SPS (it's also being printed at an absurd rate due to the airdrops everyday).
It's true that SPS won't be needed to play Splinterlands, the idea is to have everything cool withing the game require you to either have SPS staked or pay a premium to someone that has. I do like the concept but we'll have to see how things play out in the end.
Regarding the inflation rate - it's a problem short turn, especially because of the VCs just dumping what they get, but on the other hand the total print will be 3B and that's known already so people can plan accordingly. I'm not stacking SPS to sell it again anyway, so I'm not too much worried about it's short term value. Things should improve a lot once the airdrops end.