I HAVE recently bought a tablet and love it but I use it for browsing, email and reading PDFs of tabletop Roleplaying games.
But I don't use it to read novels.
BUT I also have a ereader, which I DO use for reading novels and it's perfect for that.
Couple that with the superior screen for reading text, far far better battery life, small size and weight and I don't see eink ereaders dying out anytime soon.
Whilst I have grown to find Tablets very convenient, it hasn't replaced my ereader, but it HAS replaced my laptop somewhat.