LRX is Sony-specific and it is not currently possible to circumvent its DRM (encryption). This means that you can't move LRX ebooks to any future devices, except those from Sony.
The ePub format is an industry standard, and it is becoming very popular in Europe. The "standard" part is a bit misleading for DRMed ePubs, because these are all from Adobe at present. So this means that they only work on devices that support Adobe Digital Editions. However, several other EInk devices will follow Sony in including this very soon (there is a version of the Cybook Gen3 with ADE already). For DRM-free ebooks, I think it is fair to say that ePubs are the future standard and they won't become obsolete. The good new is that you are not locked into Adobe DRM, see
Adobe ADEPT DRM for EPUB circumvented.