What do you mean by "until XP becomes unsafe"...?
It's already since a long time known to be much, much more plagued by infections and security holes than W7. There is no argument to defend using XP. It was good at its reigning time, before W7. No argument to stick to it if you have W7.
Tyrant,
I must leave you to yourself with your assessment that Windows 8 "does great". The business report numbers I googled this afternoon (again) and the feedback by tech inspectors in blogs and tech magazines from the past months on the design and handling of W8 on a PC are so fundamentally detrimental to your views, that it speaks for itself. Regarding cellphones and tablets I never said much, possible that W8 is good for them, but then again, sales of their hardware for W8 are a pain for MS. The early and significant price reduction is a clear indication. and even now they find it difficult to sell the devices. I think they are still overpriced and needless hybrid designs that make too many compromises, do too much in this and thus do nothing really good, and achieve too little in compensation.
In the end, I have not lost money to W8, will not lose it, and anyway, this thread was about Ballmer quitting.