Each time a new Link or BRT line opens, there is often a restructure in the area that it serves. I think something similar will happen when East Link opens. I also think there are too many routes serving Downtown Seattle, so some of these routes can be removed when East Link opens.
Route 550 will be discontinued, having been replaced by Link.
Route 542 will be extended to Bear Creek P&R, following the routing of Route 545. It will also have a minor deviation to serve South Kirkland P&R. It will also be boosted to 10-minute frequency during midday, and 15-minute frequency on weekends. Route 545 will be reduced to peak-only.
Route 255 will no longer serve SR 520 or Downtown, but instead terminate at Bellevue TC. Between South Kirkland and Bellevue it will take 112th Ave.
A new frequent Sound Transit route will start in Downtown Seattle, use SR 520 and I-405 to get to Kirkland TC (with a quick stop at South Kirkland), then continue on I-405, stopping at Totem Lake, Brickyard, and Bothell before reaching Woodinville.
Judkins Park/South Seattle
Route 4 will be reduced to peak-only, only going between Downtown and Judkins Park. Route 3 will be boosted to the same level of service as the combined 3/4.
Instead of running via Jackson, Route 106 will run via Boren and Fairview to South Lake Union.
Route 60 will run via 12th Ave instead of serving the hospital campus.
A combined 49/36 will run via 12th between Jackson and Yesler, on 14th between Yesler and Madison, and on 15th between Madison and John.
Route 8 will run straight on MLK instead of diverting to 23rd between Yesler and Jackson.