Actually, gravity is determined by the mass of the Earth, not its rotation. So we're safe there. But there would indeed be some pretty dramatic climate changes! But short of some collision with a huge interplanetary body, the earth's rotation is going to continue uninterrupted for quite a long time. Don't worry about it.
On the other hand, a shift from a north magnetic pole to a south magnetic pole is considered likely to occur sometime in the next 10,000 years. Important to plan for long-term as a species but not worth worrying about for us as individuals.
Regards, Vince