So here's the deal. Every so often a movie series makes it big. When everyone's contract is up they all start fighting.
Recently the actors like to take the fights public because they get more sympathy when they show the disparity between their pay and the movie's gross profits.
The studios then start talking about replacing them in order to temper expectations.
Then, eventually, they all sit down and agree on a private deal and go about making the next set of movies.
This isn't a new pattern, and its not unexpected. They replaced Terrence Howard with don cheedle from one to two, and no one cares now. Everyone was up in arms when Richard Harris died and Michael gambon replaced him for dumbledore in Harry potter, and today many still claim he doesn't fully embody dumbledore from the books, but that isn't preventing anyone from going and watching and enjoying the movies.
So the threat isn't idle.
However, just like the Simpsons voice actors every few years, this little song and dance will go on.
It's simply part of the negotiation process, and it'll play out over time.
Just keep in mind that even though an actor currently playing the part embodies it right now, that doesn't exclude the possibility that another actor wouldn't actually be better at it. I know few people who actually believe that the first person to play batman or James Bond on the silver screen was the best.
Anyone who claims the actors that have embodied the role so far is the absolute best choice possible is little more than a fanboy with a short sight.