Depends what Katya wants - she has just got married so maybe wants to take a back seat for a while. She is clearly part of the Strictly "family" and CRH is known to admire her.
The dance troupe idea is not so stupid as it gives the BBC "back up pro dancers" under contract in case of any injuries - so would have worked this series.
Ian Waite is on standby as a male backup and was used in this series.
Word from other posters is that Katya was appraoched when Aliona got injured but was unavailable/ overseas.
Ian & Natalie and Kristina do a lot of group dance choreography so are "of use" to the producers.
We, the audience, have little idea what goes on backstage with the show and dancers, who is popular, who does what they are told, who argues etc.
Don't be fooled by "stage persona" as to how the dancers are thought of by the "powers that be".
When they had the big "clear out" of Pro's, they brought in several dancers from the former Eastern bloc.
I thought this was maybe a bit like Pantos using Aussie soap stars, they do exactly what the Director/ producers tell them (in the Aussies case because they have no idea what Panto is anyway), and don't answer back or make suggestions of their own.
Katya maybe falls into this category, being born in Lithuania and growing up in Israel - where you have to do what you are told by the Govt !!