OK, then I would interpret the strategy like this:
1) Windows Phone is now "dead", to the extent that it will merge with Windows RT. This new OS will be targeted at small tablets (and possibly phablets), and thin-client netbooks. Basically a ChromeOS competitor. Accordingly it might well be a free OS (http://www.theverge.com/2014/2/28/5456374/windows-8-1-with-bing-experiment
2) The Android fork (System X) will find it's way onto Lumia devices. The goal here is to break the OHA by offering OEMs a 'cheaper' alternative to Google - they can have System X for free, rather than paying the patent licence fees many now pay Microsoft to use Android (and ChromeOS).
3) S40 will die out quietly, but while the Nokia brand is available they will hope leverage it (the ecosystem "feeder" they reference). I wouldn't be surprised if the use of the brand is somehow extended even for a short (12-24 month) period.
3) They'll target the smaller, regional OEMs in emerging markets as a key part of the strategy (Google's Project Ara is the defence here). BUT, they'll possibly have a couple of premium brands on-board. I can't see how Sony as part of the OHA is now suing other members and Google as part of the Rockstar patent troll consortium. Similarly Nokia's remorselessly and relentless attack on HTC might make sense in view of this wider strategy (HTC already pay royalties to Microsoft and Apple, adding Nokia might be too much. But if the moved to System X ...)
4) The bonus is that developers will have to do minimal work to get non-complex apps working on the new platform. They would hope to have 100Ks of apps on-board quickly, and again they'll pay where necessary.
It's basically a bigger and more enhanced version of what Amazon did, but by a bigger, better resourced, and technically adapt operation. It has a chance. If it gains any traction it'll be a test of the stickiness of the Google ecosystem.