To the best of my knowledge, neither my Dell Axim x51v, Netronix EB100, Bookeen Cybook Gen3 (either the 64MB or 512MB version) nor my Sony PRS-500 can handle ePub. Thus, I prefer getting HTML, Word DOC or RTF files so I can create the proper ebook for my devices. So yes, RTF still has a life, in my most humble opinion.
Derek