I would pretty much agree... OC is probably the worst exploratory content we've had, at its core..

I would also say, I wouldn't use Eureka as indicative of how alive or not this content will be.. Eureka has the benefit of... To do the relics, you must do Eureka.. Not only that all steps for the relic are contained in Eureka..

Step 1: You can do FATEs or you can do OC... They are probably going to increase the rate in 8/0 for FATEs.
Step 2: Has no involvement in OC whatsoever... Do a bit of crafting, do your roulettes (which you were doing anyway)

Who knows with the next steps? But the fact that subsequent relics after the one-time steps is just Tomestone grind... I would say would suggest that OC is probably going to fare worse than Eureka in terms of survivability going forward.