Some good ideas you have here. I didn't think of a tip button, but that would be a good way to reward content past the 7-day mark if you choose. Evergreen content should keep raking in rewards in my opinion, because it does on Youtube and personal blogs. The advertisement option is something to consider as well even though one of the reason I like Steem is that it's ad independent. But, again, evergreen content should be rewarded if we want to convince quality content creators to join Steem and DTube.