Yeah, the 150 'chrome' has just come out, and its basically a re-release of an older iRiver player. Its still a good player, but lacks some of the fancier features of the slimX, namely, size, and the cool remote. But its still firmware upgradeable, and plays all types of discs, mp3s, and wmas. If you are on a budget, its probably a good buy, but if you can afford the SlimX, its obviously the superiour player.
As far as the dataplay player... I'm not sure when its coming out exactly, but it sounds like it could be interesting.. It could be the size of the super tiny 'smart media' players, yet would hold 500mb instead of 64mb. And you could easily switch discs. A little pouch with a few discs in it could easily hold a few gigs of music. A CD holds about 200mb more data, but is obviously much larger.
As far as the format 'dying'.. i'm not sure about that. it may not take off as a commercial distribution format, but it could become popular as a sort of 'mini-minidisc'. Something that is used as a data storage method for small players, pdas, digital cameras, etc.
If the dataplay player was available at the time I had bought my SlimX, i would have given it serious thought, but I'm very happy with my SlimX, and so I won't be bothering to upgrade when the dataplay player comes out. If size is very important too you, it might be worth it to wait for more info on it, but if size isn't your biggest concern, the SlimX is a great player, and is in no danger of being made obsolete by any dataplay players.