The answer comes from a chat with Skype support...
This is part of the chat log. Slightly edited to improve spelling and grammar, but otherwise unchanged.
When you click 'delete' in the Skype Web interface, the system actually just unlinks the Microsoft account. You now can't log into it again. With no remaining linked login systems, nobody else can ...
Only Microsoft can answer the exact time period.
As per my knowledge after 60 days they delete all your data from the sever. Some data might take few more days or weeks to get clear from the server and backups. But after 60 days you will not be able to access any application through that account.
According to Mike Kinsman Owner Monday, August 29, 2011 8:01 PM:
I think you're asking how to switch your MSDN Subscription to a
different Windows Live ID. Is this the case? If so, this is easy to
do, you can just take your subscription information (first name, last
name, email address on the subscription, and your Subscriber ID).
You also ...