Hell no. The time to rebuild is after a year or two of being middle of the road and not competing for the playoffs while still having assets that people want.
We're coming off 2 straight playoff appearances, have potentially a top 5 rotation, and a mix of controllable talented youngsters (Osuna, Sanchez, Stroman, Travis) and aging (but still talented) stars (JD, Tulo, Martin).
There is no reason why we should sacrifice the next 2 or 3 years now - we could make the playoffs this year with a bit of luck, and still be able to trade people like Tulo and Donaldson next year (EDIT - if we wanted to) when some of our prospects will be more ready to take their places.