Open core in data isn't even close to new: We've had companies contributing to OSS databases, while selling extensions with a bunch of extra features, back when noSQL was all the rage. Back then, I was called to rescue a large distributed system where the architect had bought on the commercial offering, and managed to rely on basically every single feature in it. He hired his engineers from the conference circuit, including some that had written books, thinking this was giving him a good talent. And yet, the system wasn't working well at all: Almost everyting appeared to work on unit tests, but nothing worked well in production for hard to track down reasons.
Given the instability, I started by mistrusting everything in the system, and it didn't take me too long to realize that every single extension feature from the for-pay distributed database wasn't actually doing what it said on the tin, or it performs orders of magnitude worse than anyone expected. Only the open-sourced features, which had been used in production all over the place, and had received sufficient patches to be reliable. Everything that we were actually paying for was mostly worthless, and needed to be engineered around. The real value of open source here had been a very large user base that guaranteed a semblance of quality. Since for-pay features were available only to the few for-pay customers, the company was faking it until they made it... and there was a lot of faking.
This is the ultimate problem of open core v profit: the quality of the OSS has to be rally high to get any actual open acceptance, but every second spent on the OSS system is one you aren't spending on the parts that get you revenue. If you make the OSS system too hard to use, there's little value from the OSS bits, but if all you are missing is a tool or two, someone can build open replacements, which might actually beat yours anyway.
It's not absolutely impossible to end up with a working company like this that is more than a glorified consultancy, but the success rates are just very low. The fact that this is true, and well known, also makes people purchasing tools be wary of the model, you don't want to build your infrastructure around a tool that quickly goes on life support. So all in all, going for this model is quite the gamble.