  After decades of effort, the solar activity cycle is exceptionally well
characterized but it remains poorly understood. Pioneering work at the Mount
Wilson Observatory demonstrated that other sun-like stars also show regular
activity cycles, and suggested two possible relationships between the rotation
rate and the length of the cycle. Neither of these relationships correctly
describe the properties of the Sun, a peculiarity that demands explanation.
Recent discoveries have started to shed light on this issue, suggesting that
the Sun's rotation rate and magnetic field are currently in a transitional
phase that occurs in all middle-aged stars. Motivated by these developments, we
identify the manifestation of this magnetic transition in the best available
data on stellar cycles. We propose a reinterpretation of previously published
observations to suggest that the solar cycle may be growing longer on stellar
evolutionary timescales, and that the cycle might disappear sometime in the
next 0.8-2.4 Gyr. Future tests of this hypothesis will come from ground-based
activity monitoring of Kepler targets that span the magnetic transition, and
from asteroseismology with the TESS mission to determine precise masses and
ages for bright stars with known cycles.
