She's popular, and people often listen to her simply because it's "classic," which automatically makes the listener "smarter" than "fans of Russian rock/rap/any other music."

Those who listen to classical music out of snobbery rarely go beyond "The Turkish March." It's hard to imagine someone listening to Rachmaninoff's concerts if they don't like symphonic music.
Moreover, the influence of fashion or prestige on musical tastes weakens with age: it's unlikely you'll find 40-year-olds bragging about who has better taste in music. At that age, people compare cars, apartments/houses, and incomes.

Maybe classical music CDs are given away for free 24/7 in Moscow, but unfortunately, this isn't the case in other cities.
Are "tributes" being made? Sure. Are they being sold? Of course.
So, "in a way, it's pop music."
That's my opinion.

And how are music sales related to its author (in the case of classical music)? Does Mozart receive money from the sales of CDs in Moscow? Many classical works didn't bring their authors a single penny. Great composers simply gave music lessons or worked in orchestras; that's how they made a living.
Especially if we're talking about religious music – and most classical composers wrote religious works. Of course, these weren't sold to churches: on the contrary, it was an honor and a joy for the composer that his work was played during services.

How do sales change the genre of a work? One of the most expensive artists, Van Gogh, sold only a couple of paintings during his lifetime. The millions-of-dollars-worth paintings of Gauguin were not wanted by the merchants, with whom Gauguin had nothing to pay with. And did this "alternative" suddenly turn into "pop music" just because it started selling for a fortune? Did the colors in his paintings change?
The same goes for classical music. Great composers, who died in poverty, didn't write their music because it was commissioned and paid for. It's not like Igor Krutoy, who writes-sells-writes-sells... They didn't expect to get rich, let alone simply live off the income from their works.

And what difference does it make who sells their music now and for how much...