I cosign everything in the OP article regarding logistics, current availability, the Vientiane Gap, etc. The only thing I'd note is that there's a different route available that is about 1000km shorter, via Barcelona-Nice-Milan-Venice-Vienna-Bucharest-Istanbul-Baku-Astrakhan-Almaty-Urumqi-Kunming-etc.

I've done nearly the full Trans-Siberian and while it's a cool experience (esp if you speak Russian and can talk with people on the train), watching pine trees go by gets boring after day 3. I personally think that if you're going to commit to a Europe-Asia train trip, it's better to take the scenic route.

The even more exciting option will be when China finishes the Dushanbe-Kashgar and Lhasa-Chengdu railways. That will facilitate an absolutely epic ride through the top of the world.

I did that Thailand night train back and forth to Surat Thani at least a half dozen times back when I'd spend my winters there. It's probably my favorite of the bunch for sheer atmosphere.

It's a shame that night trains in general are vanishing these days. You used to be able to do Europe without ever staying in hostels, hopping the longest train you could find each night and waking in a new city.

Now you can go back and forth between Paris and Venice, and that's about it.

The advertised Vyborg-Tver train is a scenic route which runs once in a blue moon.