I'm an avid Splinterlands player myself, but the truth is that Hive needs something else besides Splinterlands. The game will keep growing, yes, but the ecosystem needs something else: other games, more posts on the social media, more token transactions etc. All those things, together, will bring the RC usage up (together with Splinterlands, of course).
In other words, I don't feel safe that 90% of the transactions on the Hive Blockchain are related to a single app: Splinterlands.
!1UP