Strictly speaking, the the impression you just expressed is false. It's unpurchaseable (new, anyway) now, and will probably stay that way, but they were sold together for quite a while. (It seems pretty natural that products introduced earlier will be taken out of production earlier.)

The N810 WiMAX and non-WiMAX probably will be sold side-by-side, and the next product could be any of several options without being a "direct replacement" (or "N810 successor"): It could be an N800-like device (indeed, a direct replacement for the N800), it could be a GSM-connected device (<gasp />, a phone!), with the N810 left for carrier-independence, or even a line-up of devices covering the whole range.

If one wanted to read altogether too much into "That platform is still new and it is still finding its way.", the N800 successor could be eliminated; while I don't think that's justified, I also don't think an N800 successor is especially likely.