Ferrari Land is apparently 14 acres, which is the same size as WWoHP at Universal in Florida. Not sure which of the areas this is, but it's one of them. You don't see Universal charging $25-30 extra on top of park admission for the Harry Potter areas, do you, PortAventura? While WWoHP is admittedly a bad comparison, the point I'm trying to get across is that Ferrari Land, in its current state, is too small, in terms of ride quantity and things to do, to function as a proper second theme park. What PortAventura need to do is they should add a couple more rides and maybe another coaster or two to make Ferrari Land better value. And they're going in the right direction by adding this kids' area, as it will bolster out the park's lineup and get it closer to being a full day park. After this kids' area, I reckon Ferrari Land could do with another roller coaster. I reckon a Mack family launcher, similar to Slinky Dog at Hollywood Studios, would work well. Or they could even opt for the Mack megacoaster ride system and make it a family ride, like SeaWorld San Diego did with Manta. Theme it to cars and name it something like Ferrari F40 Test Track and they're on to a winner. While we're in alternate PortAventura, they could also add a non-simulator dark ride, maybe something akin to Speed of Magic in the Abu Dhabi Ferrari World on a smaller scale. Or if they wanted to be weird, they could do an indoor log flume, like the now demolished V12: Enter The Engine in Ferrari World Abu Dhabi. Then, I reckon Ferrari Land could be done for a while.
Ferrari Land looks like a lovely base for PortAventura to expand upon, it just lacks rides at the moment.