I can see two potential views on this.
1) - If they want to actually sell lots of 920's, then it's a bad strategy IMO. As above.
2) They DONT want to sell lots of 920's, however they do want to sell lots of the lower-down models for cheaper money.
Think about it in car terms - Nissan have just released the ridiculous Juke R, costing £400,000.. I dont think for a second that they will sell many, or indeed make any profit on that line, but the purpose is to get headlines, magazine space, and implant an image in the minds of potential customers of the low cost Jukes of 'cool' (or something).
Apple themselves play the 'halo' effect with skill, enabling some type of 'desire by association'.
My opinion - for Nokia, this is a very high risk strategy, that could see people turning their backs, and Nokia going broke. It'd be a shame.
My wife has just got a Lumia 800, since it was free on her £15 a month contract, and I am very impressed on the whole - it's certainly made me consider a Windows Phone for the first time for my next upgrade in a year, which if I hadnt have played with it personally and gotten a feel, i'd never have considered it.