ROI stands for Return on Investment. Universal's investment in Lost Continent has ready paid itself off, like fryoj said. You cant lack ROI if you havent made an investment, which IOA hasnt done to Lost Continent in 15 years lol.
Wrong phrase
.. they're not selling merchandise to the levels of other IPs like Potter, Transformers, Simpsons, DM, Seuss, Marvel, JP, etc. without Mythos, LC is just an average stunt show and slightly underwhelming if satisfactory walkthrough. But it's obvious Universal Creative has proposed replacements for this area before (more Potter, Grinch, Wonka, etc). Mythos is what keeps the land remotely relevant now that LC's former two rides are Potter themed now. Mystic Fountain is a great feature, but the lack of a ride hurts the repeat factor. I remember being a kid and going on Poseidon, assuming it was a ride based on how beautiful the exterior was... then I saw the show. I was annoyed. It was okay but it just screamed dark ride to me.
They're high capacity and eat crowds, so they'll be great for the rush these next couple years. But IOA is sorta landlocked. And draining the lagoon for expansion space would be a bad move. So you've got 3 real areas to grow not counting Kong. TL front area, land by Cat, TE/Discovery Center area. Unless you remove something. Dragon Challenge will stay for a good long time, Dudley is enjoyable but lacking in theme, and LC has become so tiny.
The Greek/Arabian theming could also work in WonderSea Island. LC would work well in a waterpark. Poseidon's temple as a slide, maybe a flume ride? A pirate lagoon with a slide for Sinbad. Plus the theme wouldn't feel so hacked up. And Grinch is getting a new movie November 2017, so if that's successful, there's more incentive.
LC shouldn't be a first priority, obviously. Kong, JP, Toon theater/front area, Seuss, nighttime show... Those should come first. LC's a beautiful, if barren and small, section of the park that has two of the park's 5 indoor attractions. But as expansion options are limited, I definitely can see LC getting nixed. Not now, but later down the line.