Ya, the EB is pretty much over 50% full either direction; sometimes you can not get a seat.
On the upside, BNSF has been double tracking starting @ Wenatchee and has made it East to Sandpoint with parts still single track. West Spokane curved bridge over Latah Creek ( actual wye in the middle of that bridge ), East of Irvin ( Pines road Spo Valley ) over Spokane River - have seen new construction and suspect that a 2nd bridge is forth coming. I have not chased West of Spokane for quite awhile, so I can't tell ya what is there or missing. Spokane South to Pasco has long segments of 2MT, then only through the tunnels on the river are 1MT. The EB splits and joines at Spokane, 1/2 to/from Portland, 1/2 to/from Everett/Seattle.
Used to be the all that was run over Stampeede Pass was oil and grain. No double-stacks as the bore would have to be cleaned up height wise; something like they did with the Cascade Tunnel in the 90's. I guess they could run 'selected' merchandise with height restrictions.
From Sandpoint still single track with sidings but working on the RoW to widen for 2MT on the hi-line. xNP, xMRL to Missoula probaby won't see any passenger service although it kinda gets in the news every few years or so. Hi-line has problems with the Kootenai Canyon and of course the Flathead Tunnel.
All of that *should* help keep the lines clear. Seeing 40 trains a day through Libby. Used to be 50 - and a ton of 'riding the yellows' going on. Most of the dead time is daylight hours.