I'd probably choose the bigger market over the smaller one. As an investor/stakeholder, why shouldn't I?
You invested in Steem token not Steemit token. Each company has multiple teams (which sometimes are working on the same engine), but another idea should not always be incorporated in the most well known product of a company. Youtube is still a Youtube, not a Google Video.
Of course, one product of a company can/should promote another products in a common ecosystem, but this not mean, that those two products has to be merged for ever.
As a investor you should remember about diversity. If Steemit.com will fail, I would prefer to have still SteemSports.com thriving, but if SteemSports will fail, I do not want to see Steemit taken down together with it.
They're all using the same blockchain and therefore drawing from the same pool of content. If Steemsports switches its primary interface to steemsports.com, the posts will still appear on Steemit.com. Steemit.com is a view of the blockchain, it is not a separate platform with its own content.
Steemit decided to hide content which is flagged by many people. This is just a policy. Another policy can be: hide everything with content-type: games, because there is separate interface dedicated for that
Of course, but why would you do that on a leaderboard of the highest payout posts (which is what the badly-named "Trending" represents)? Steemit.com can offer a different home page with whatever sort of filtering rules, and indeed I think the biggest problem with this platform is people can't filter and display what they want. You can't even look at one person's blog without seeing resteemed posts, nor can you look at posts with one main tag without seeing posts using the same tag as a secondary. The entire organization is terrible. But this has very little to do with Steemsports, which are not only games but also (sport-oriented) blog posts BTW, so it isn't even clear to me how that would be categorized if it were possible. Some other game posts are more clear though.