For that we need new content that is attractive enough to attract a steady amount of players into SE which a portion of could make mods to maintain a large and steady community- like with Minecraft. Problem is the rate of updates, which are adversely affected by the rate of donations.
Yeah, you're right.
The problem that affects both Minecraft and Space Engine (this one in particular) is that there is not a clear
goal. Why does a lot of people keeps playing many FPS games even if they're not frequently updated? Because
there is a true game in them. Space Engine it's not even a game, so the most interesting thing you can do, in a YouTube video for example, is showing off the latest features. That's why people keeps being interested in Yandere Simulator, because they want to try to latest things that have been added, then... they just close the game or get bored very easily.
I'm not saying Space Engine is boring, I'm saying it doesn't have a goal, and it's not as easy as Minecraft or Kerbal Space Program to create mods. You can't just "create new gamemodes" or things like that, the best you can do is creating systems, spacecrafts or interface/graphics customizations.
So the planetarium will never become popular. But the game that will be made using Space Engine might, even because there is already a community behind the engine and a lot of people knowing the project. The problem is that this game doesn't exists, and I'm not sure Vladimir has a clear plan for it.
I've had few plans, but the one I think would be most successful at accomplishing this is social media (i,e sites like Reddit would be a good example.)
Yeah, this would indeed be very useful! Making SE into a meme it's impossible, but trying to do so would definitely help spreading the word.