Naming conventions and market forces
I am a bit upset at the D5000. The new naming will help with future gen camera bodies such as the next D90 and next REAL D60. What makes me a bit upset is the poor LCD on the back of the body. It's one thing to have the 3.0" 920,000 pixel LCDs on every body from the D90 and up, then not put it in the body between the D60 and D90...... which has D90 features that would have welcomed the larger sharper screen.
Live View wasn't amazing on the D90/D300/D3, video quality was decent but use was awful on the D90..... so now we have both on a the D5000 with a not as good screen.
Maybe I am just nitpicking.
IMO we may see a new naming convention from Nikon. The Dxx system was too limiting, and confusing. You had the D70/D70s, then the D50, D80, D40/D40x, D60, and then the D90 - with the feature/value of each being all over the map.
Having been around for awhile in the camera shop business; Nikon in the past used "N" and "F" to denote their different lines for their film AF bodies. For some reason they seem trapped with staying with the "D" designation for their DSLR's - even though they have drawn the line with their use of the "DX" for APC sensors, and "FX" for their 35mm sized sensors.
The thing is that the DSR market is maturing. The fact that the D40 still sells well at the $400-$450 shows there is demand at that price point. And that is still after 2 1/2 years on the market.
What I see when the last of the D40's and D60's are gone. And maybe when the replacement for the D90 comes out is some like this:
D4xxx - entry level, low price point under $400 at current price points - working down to under $300 in a year or two
D5xxx - a step above the D4xxx series, competing in the under $700 range by the end of the year - working down to the under $500 in a year or two
D6xxx - a platform where the D90 now sits, in the $900 with lens by the end of the year - down to $700 in the next two years
Dxxx - for replacements for the D300 - there was never a replacement for the F100. The D100 was announced in 02/02 - though IMO it did not deserve the Dxxx moniker, the D70 seemed to be of the same build quality... The D200 was announced 11/05 sort of mid way between the D100 and D70 series, with the D300 being announced in 08/07 - so we may see the Dxx moniker till 2019 with the current pace of the Dxxx series. Though I think that will slow down as time passes.
Dx - This would be hard to replace given the the 1959 thru 1996 series of the original F thru the F6... 37 years for just six models. In Just 10 years we have been through three distinct models and their variants.