When was the last time you or anyone else here went to YouTube to look for content on its Trending page? (I bet few people knew that even existed).
A Trending page consisting mostly of Steem-related posts is, imo, only a problem when there are no other interesting places on Steem to look for content. I would hope that with communities, the global trending page will not be seen as the main attraction on Steemit, but more a special interest place.
My point is that the idea of a Trending page is not really worth pursuing in and off itself. People want to see what they want to see, not what stakeholders and voting circles tells them they should see.