The touch of death for a live service game is to make it like destiny rather than warframe in terms of FOMO
What this means is that regardless of any of Warframe's or Destiny's different features or styles of gameplay, by far what keeps Warframe alive is the fact that FOMO is basically nonexistent. All content is always accessible all the time, and if you want to fast-track to something you can but you can also just, work your way up to it at your own pace. My partner and I will take regular breaks between month-long obsessions with the game, and I think that's how live services should work, to be honest.
Meanwhile Destiny will vault shit you paid for and might not have even reached yet, depending on the speed at which you go through content