Nokia's best option was the Windows Phone OS. If they went for Android, then they'd just become another Android manufacturer with dismal sales like most Android manufacturers these days except for Samsung, LG, and ZTE.
Also, it was inevitable that their mobile phone shipments would be down YOY since most of their sales have never come from smartphones.

I read that they plan to use the Tizen OS to connect all the devices in your home together and all can be controlled from your smarthphone which makes sense since Samsung produce so many home appliances, TV's, etc. 

I hate function locking patents. It's like if the developer of penicillin patented "a drug that kills bacteria" and then demanded royalties from every other pharmaceutical company that develops different antibiotics. Or JRR Tolkein patenting "a story about elves, goblins, dwarfs and people" and demanding royalties from all the derivative stories that Tolkein inspired.

Software should be subject to copyright, not patent. If you use the copyright holder's code then you pay. If you write your own code that performs the same function then you are free and clear.

Samsung's YOY increase is bigger than total sales of other manufacturers except Apple and Nokia, lol. Nokia will soon join the others if they keep going like this. The situation will be like this for the foreseeable future as well. It is inevitable.

I hope that people will notice HTC One this year. It is almost perfect. I'd like a removable battery but if you're not buying Samsung you have to deal with it I guess. Xperia Z also seem to be going strong but it has its flaws. Hopefully they will be ironed out next year.

Tizen isn't for the high-end phones. Samsung will not ditch Android, they will simply remove Google branding and any dependence on Google (as we see with the S4). The underlying tech of Android is perfectly sound and not worth replacing.

It does seem this thread got sidetracked onto talking about WP8, and not Nokia's hardware performance. It seem that Nokia is not really seeing any substantial return to relevance in the phone market. Most of their phone sales are still in the non-smartphone area, and smartphone sales are stagnant, with WP8 sales not coming close to compensating for the massive decline in Symbian smartphone sales.

11.6 million smartphones sold in Q1 12, 6.1 million smartphones sold in Q1 13. Yes, that's a substantial growth in WP8 handset sales, but for Nokia as a handset manufacturer that's truly awful. They are continuing in the direction to irrelevance in smartphones. Symbian was always going to die as a smartphone OS, so Nokia had to do something. They took a gamble on hitching their wagon to WP, and so far it doesn't seem to have done them a lot of good. Though it has kept them in the smartphone game longer than if they'd tried to stick it out with Symbian.

Would I be right in assuming that Nokia WP8 sales (5.8 million) are about on par with Sony Xperia Android sales for the quarter? I do hate seeing sales data where smartphone sales are mixed in with non-smartphone sales. Apple sold 37 million smartphones, because that's all they sell. All the other companies sell a mix, so it's impossible to separate out for the purposes of analysing the smartphone market. For instance, is Samsung a bigger smartphone seller than Apple for the quarter? That chart in the OP doesn't tell us.

It makes no technical sense to stop using Android.

Perhaps they just wish to upset Google and get concessions from them on what they're allowed to do with Android?