The real reason is that they don't want to participate. The financial reasons are certainly not the case, because if RTCG (the Montenegrin broadcaster), for example, has the money, RTS certainly has it as well. What is the background though............I don't know. It could be that they are in a total chaos now after Tijanić's death but also a complete lack of interest for ESC.
I heard from reliable sources (several of them) thet they were offered help from other TV stations from

but they refused it. They also refused help from some performers who agreed to go internally and finance themselves on their own.
When it comes to ESC, RTS is extremely amateurish. Even last year they did everything so poorly that even such a mediocre song, like it was, wasn't given any single chance to leave better impression on the auditorium. If it was for me only, I would have sacked each and every one of them.
Not to mention their censorship on the website that is working even now, and I am now actually watching how they are removing those comments of disappointed people and leaving only those that approve it. That is what they are best at.
They are complaining how people don't want to pay for subscription fees, and they don't ask themselves whether they deserved it or not. I was one of those that always paying, but I am completely not satisfied with neither the program scheme nor RTS as RTS. If I am going to continue to pay the fees so that I can watch reruns of shows from 90s and 80s ONLY............then, sorry, but no thanks, forget about paying from me too.