Well yeah, that's why their original plan was her only to live nine years anyway. So even if Kes stayed in the show for 7 years, Kes fans were going to have to deal with her dying anyway. Besides, she was going home to die anyway.
Where was this?
I saw hints that they were cutting her ties by mid-3rd season. Regardless of the line in "Future's End", the interaction of Kes with other cast members and her lines decreased. By end end of 3rd season, Jen Lien had the fewest lines of the entire cast. Harry Kim even had more dialog and screen time than Kes all season long.
It's not sure that "Kes fans would have to deal with her dying anyway". There were hints of prologing her lifespan and even if not, she would probably have survived until they arrived to Earth. As for the sick, morbid episode made to insult the fans in which "she was going home to die anyway", we don't know if this really happened. In fact we don't know if that pathetic creature with very little resemblance to the real Kes really was the real Kes.
If we look at season 3, Kes was the main character in two episodes, "Warlord" and "Before And After". She was a most prominent character in "The Swarm and "Darkling" and had a lot of screen time in episodes like "Basics#2", "Sacred Ground", "Coda" and "Scorpion#1#.
Compare that to Harry Kim who had one episode where he was the main character, "Favorite Son" and two episodes where he was a prominent character, "The Chute" and "Alter Ego".
We can also compare with Neelix who had one episode where he was the main character, "Fair Trade" and one episode as a prominent character, "Rise".
If we compare the episodes where Kes played an important part, like "Warlord", "Before And After", "Darkling", "The Swarm" and "Scorpion#1" with those with Kim and Neelix as important characters, we can see that Kes is a head of both Neelix and Kim when it comes to importance for the episodes as such and when it comes to save the day for the crew.