Blade Trinity might have been ok if it was focused on Blade, but it seemed more concerned with setting up other characters for a spin off (It didn't help that Ryan "horrible HORRIBLE!" Reynolds was pooping up the screening. It pleases me to hear he's developing a box office poison reputation).
As for a Blade 4...I'd be down with that IF it kept the focus on Blade himself (No I don't care for any spin off characters dammit!) and kept its distance from the MCU. I wouldn't want the film to be half excuses for why the Avengers and the Netflix hero crew aren't fighting vampires half the time.