Some MySQL users are looking for any sign that MySQLs end is near and are already prepping for a quick move should that happen. One fear is that MySQL will be turned into a closed source, paid product. Their reasoning is that Oracle doesnt do charity, and also doesnt respect open source because it wont make them money. Believing also that Oracle will have difficulty keeping its promise of enhancing MySQL because it lacks competent people for the job.
On the other side of MySQL enthusiasts are those who believe Oracle speaks the truth, saying it wouldnt be wise for Oracle to damage what could be a feeder database to Oracles commercial offering. Everyone is really guessing the outcome, but some would be greatly surprised if Oracle went to the extremes either shutting down MySQL or actually making major development efforts.