Почему обозначен, как ожидающий исключения?

A similar vehicle is also present in Erfurt.
https://transphoto.org/vehicle/31891/
As in Switzerland, there are very strict rules in Germany on the maintenance and overhaul of trams.
https://transphoto.org/photo/1566108/
So it is likely that this vehicle is in need of a major (legal) overhaul and its costs will outweigh its benefits.
Here, this is quite obvious, as a similar vehicle can be hired as a bar-tram. Of course, the vehicle will not be scrapped: funds for revision can always emerge, e.g. for a parade or from some other authority.

То есть его вполне могут передать в другой город в качестве музейного вагона?

Each tram can be transferred to another city, if there is mutual interest, money and space. This has to be a two-way process: the selling party has to be short of money, interest and space, and the buying party the opposite.
I have no knowledge that the tram is for sale, nor that anyone would be interested in this model or would set up a static museum: it is the only place this tram can go now, unless someone wants to pay for its overhaul. But this has already been explained above.

Так вот какая модель мелькает в фильме Э.Рязанова "Старики-разбойники". Фильм снимался во Львове.
So that's what kind of model flashes in E. Ryazanov's film "Old Robbers". The film was shot in Lviv.