No idea about outside the ecosystem, but it's certainly perceived as such by some parts of the splinterlands community. That perception is flawed though. A bunch of custom_json transactions don't mean anything by any relevant measure.

Hive keeps working without splinterlands and/or hive-engine. If they want to split they would have to rewrite their whole systems though, and even if they could find funding for that there's still the issue of transaction fees on alternative chains.

IF splinterlands players would power down their SPS to invest into hive, that would crash the splinterlands economy, and send hive. There's not a lot of liquidity for either of them.