seeing their multi year revenue and compared to other mining pool, Binance pool is pretty low and only have 1% hashrate, so it kinda make sense they shut down the service.
I thought about this too, if really they were making massive profit the binance pool, I don't think they would want to shut it down, although they didn't release any information that mentioned if the reason for closing the service is financial problems but logically, if they were profitable in keeping that service activite, they won't close it, I guess they have seen better opportunity that fits the company's vision more than these ones that they are about to close and like you said, they could be moving to something else that will make more billions for them.