I think there is truth to the notion that losing Lost Continent entirely will kill a good part of the original Islands of Adventure's unique visual and tonal identity. Yellow parchment, sandy shores, clay buildings, grand ruins. I believe it will feel like a different park without it.
Merlinwood -> Harry Potter was a rather 1:1 translation of visual and thematic identity. It was a very solid design decision that kept the general vibes of the park intact, with a significantly more popular fantasy world of wizards and dragons in the back, while the front half of LC retains its' mediterranean and Atlantic stylings that flow directly with the semi-adjacent Port of Entry.
I do think it's for the best, as Lost Continent is a literal shell of its' former self currently. Outside of that visual flair, it very obviously isn't pulling its' weight as a land. That said, it will still be a loss, and maybe one that we will look back on as some kind of turning point for the resorts' history.