I wonder if this is not a case of horses for courses? I use both, but for very different purposes. Both are good ways of following touring cyclists and their adventures. Both are great and very cheap ways of keeping friends and family up to speed with our cycle travels day by day. Can I image the world without them? Sure. Will they last five years? Well, frankly five years is a lifetime in technology terms: I doubt that any of us can imagine the technologies we will be using then, but for sure unless we see some horrid turning back of the tide, we can be sure that FB mark 5 and Twitter or their currently unimagined replacements will be augmenting our worlds for certain. The future's bright: the future is....presently unimagined.