I wonder how contract negotiations will affect the future of the show

As far as we know, the actors are only under contract until season 4. If the show gets renewed for 5 and/or 6, they will have to renogiate. Given the success of the series, I think the actors are all within their right to ask for more money, but will Netflix give it to them or will just they just decide they don’t need the actors who have already had their seasons.