For reference on the whole subject of commercial passenger aircraft operating at supersonic velocity and why nobody makes them even though they are definitely within human reach see this:
A shorter summary of it is that it's just not
maximally profitable.
Commercial/passenger aircraft are for business first. In other words, it's all about the money.
Problem is, that there was no viable way to make a profit on this plane in the long run.
Initially, the plane did make a profit, but that was because it was the new cool thing that everybody wanted to try. So the demand was high enough that they could stuff people inside of it like sardines packed to the very rim.
Stuffing this many people inside each and every plane ride was the only way to make a profit, and even then the profit margin as well as gross revenue per flight was just not as good as many other aircraft and flight routes who have had long established history of success.
Therefore, even if profit, revenue, demand, and the novelty "ohhhhh wowowowo cooooool" factor of this type of supersonic flight had stayed forever (not possible at all BTW) it would've simply made more sense to still get rid of the this kind of plane since your company would be making more money going with other planes.
Of course, the novelty wore off so demand died down. Each flight eventually became ledss and less filled with passengars, a.ka.
paying customers, until it actually was a loss to operate. A loss per every flight.
Biggest reasons why this type of aircraft has such difficulty being profitable is:
1) Initial upfront cost is already overly-excessively high due to the challenges of supersonic cruise.
2) Supersonic velocity also means
tremendous maintenance, repair, and upkeep cost due to the strain, stress, and wear/tear on the plane because of this inconvenient thing called physics.
3) Obviously, this is going to use a lot of fuel to do supersonic cruise.
4) Physical limitations mean that the plane cannot 'stuff' as man;y people since it has to fly supersonic, fuel tanks need to be big to fly supersonic once again, not a lot of room for baggage/luxury stuff that makes the flight enjoyable because of need for big fuel tanks and 'slim' design to lower air frction drag/slowdown.
5) Stuffing passengers this densely means that people end up not enjoying the flight and just overall don't like the whole experience because people are awkwardly packed too closely to strangers sitting in small seats with uncofortable posture...even under 'normal' flights nobody actually likes flying but now it's even worse.
6) Lower number of both business and first-class seats means that you are losing the very best profit-per-booty (I had to, LOL)....seriously though, commercial passenger flgihts basically don't care about coach class. In fact, they don't even care aobut first class as much as you would think. It's business class that they care about. Because Business class section is where they make the biggest profit. First class is so spacious that the first class cabin cannot stuff enough customers to make as much money as business class. But business class is the perfect balance between taking up square footage vs revenue per customer. Additionally, business class customers are disproportionately composed of people who are getting their flights paid for
by their employers or at least not themselves. Therefore, they end up spending a ton of money on luxuries/random stuff while flying. And unlike first-class customers whom are more easily upset or dissatisfied and thus take their business elsewhere, business class cusotmers typically have little to no choice but to accept whatever their employer offers. Additionally, since it's usually employers buying the flights this means that they typically have a long establishd business relationship with the flight company...meaning a stable and long term source of income/revenue for the company.
All in all, I don't doubt that the Russians are capable of making this succeed in purely technical terms, but the problem is, as always, the fucking customer...they're just too damn hard to please, too easy to upset, and too much power in the business relationship if they start working in numbers.
But who knows. It's been decades since the original Concorde, and that's equivalent to an eternity in technology. Maybe things have changed enough to lower the costs of operation of this platform or have improved the overall experience enough to change consumer's minds.