Yes it remains to be seen what Oracle will do with MySQL. Will Oracle see it as a threat to Oracle Database and try to smother it or will Oracle see MySQL as more of a threat to things like SQLServer and use MySQL as a way to keep Oracle shops on the Oracle brand.
While MySQL may cost Oracle some revenue on the low end of Oracle Database, I’ve seen many Oracle shops use SQLserver for smaller , so-called departmental loads to save on licenses and admin costs. (Or at least a perceived saving on costs, that a whole other discussion.) Using MySQL would “obviously” save even more and cut MS out of the picture. There is a lot of value in keeping the competition’s sales person out of the building.