> at this rate the Earth will stop rotating in 50 billion years,

That's not what the link you posted says. It states that that's when the Earth-Moon system will be tidally locked, so that the Moon orbits the Earth at the same rate that the Earth rotates around its axis.

Kind of if the earth slowed so that one "day" took the equivalent of 28 days now. The earth would be locked with one side always facing the moon, so there would be no tides, but it would still be rotating. Except it will end up be a longer "day" than that, because as energy is transferred to the Moon its orbit is raised, which slows it down.