I went out today to verify that the "closed" section of the Three Cape Scenic Route over Cape Meares is still rideable. It is. The only difficulty is 150 feet of hard-packed gravel that you will probably not even dismount for. By taking this route over Cape Meares you add 5 miles of beautiful riding right on the shore of Tillamook Bay, The Cape Meares Lighthouse, the spectacular and iconic view of Netarts Bay, and the quaint towns of Oceanside and Netarts. All this riding is on low-traffic or no-traffic roads. Truly some of the best on the Oregon Coast Bike Route.
The State recommends staying on 101 through Tillamook and turning right on Sand Lake Road. This is mostly safe except for a perilous short section of 101, fewer miles, less effort, and very boring. The ACA recommends taking Tillamook River Road south from Tillamook then Ekloff road. This adds 10 times as much riding on gravel than going over Cape Meares, with the added benefit of meeting logging trucks on a narrow road. Because of the Cape Meares "closure" many cyclists just take State 131 from Tillamook to Netarts Bay -- a very dangerous section that has claimed the life of one experienced touring cyclist.
The Cape Meares route could become impassable if the slide progresses this winter. And at some point it may be under construction. But at the moment, and for the last 6 years, it is very passable.