I think they never expected to remain in hiding for 17 years. Obi-Wan original plan for Luke was probably to use him as bait to lure Vador to Tatooine. Otherwise why name the kid Skywalker anyway? But as fate would have it that not going to happen. Yoda and Obi-Wan, in A New Hope and Empire give me the same vibe that deposed rulers have after spending 20 years in exile. They like to pretend that they go back as liberators, but by the time A New Hope start they lost all illusion of doing that.
from overview for madhi19 http://ift.tt/1t0ShRB