Gone are the days when turbine manufacturers were reticent to offer more than 3 to 5 years of bumper-to-bumper service contracts. Now we are seeing 15-year full service contracts. This is huge for developers because it reduces uncertainty of both energy production and O&M cost, thereby increasing financeability of a project. In addition, the cost of O&M has fallen 30% in the last 5 years. For more see, http://analysis.windenergyupdate.com/operations-maintenance/turbine-supp....
With lower PPAs and feed-in tariffs, the push is towards lower and more predictable O&M costs. With data analytics and more efficient supply chains, it is predicted that the costs will fall 20% in the next five years. See http://analysis.windenergyupdate.com/content/wind-om-dallas-2016-keynote....