Sega killed Sega.
The Dreamcast was never going to save the company, just postpone the inevitable.
This is pretty much true. Sega failed with the Sega Saturn and had to release the Dreamcast earlier than the competitor's next gen consoles to get a head start. After the PS2 release, Sega tried to compete with Sony, but failed big time.
Pretty much the same thing would happen again if they made a new console. I'd like to see Apple make another console, despite the Apple Bandai Pippin being a failure.