Shaw Wu from the Kaufman Bros. analyst firm has claimed that a 9900-series BlackBerry is in prototype phases, packing a touchscreen slider form factor. The supposed device will mix the traditional BlackBerry style with the Storm, which makes me think it’ll be a portrait slider like the Palm Pre. Now, I’ve been calling for a slider BlackBerry for awhile now, and there have been similar rumors floating around about the 9100 Striker (although it’s in the Pearl family) and the landscape-oriented Mr. T; patent designs from RIM certainly show they’ve been thinking about it, but I’ll believe it when I see it. This new Storm 3 device has a lot of potential for appealing to consumers who still hate SurePress for typing, although it would go against the slim and trim look the latest BlackBerrys have been adopting. In any case, the 9900 should be landing sometime in 2010, according to Wu’s contacts in the supply chain, so cross your fingers.