There's no way in hell this is ever going to happen, espically considering how much effort went into creating and distrubuting UMDs. I would hate not being able to have a physical copy of games I buy. A download-only method of selling games will put off LOADS of potential customers for Sony.
PSPFanboy has been talking a load of rubbish lately IMO. Not that I dislike the site at all, I use it regularly.