No they are not blocking the MSNP21 protocol. You can see that in all servers that have MSNP21 red crossed, the port 443 is red crossed as well. Microsoft would not block port 443 since Skype use it. That probably means that these servers are offline or under maintenance. That happens quite often.
I recently checked the messenger server status,
and it looks to me, that Microsoft is also slowly shutting down the msnp 21 protocols.
Idk if this is just for maintance, or permanetly, but with the lauch of Windows10 right on the corner, it looks to me that Microsoft has other plan´s with the messenger servers.
I think they might have a new protocol ready, for skype and new apps.
So im not sure, what this all going to mean for the future of wlm2012.
There is a fair amount of evidence that MSNP21 will still work. They had not blocked the protocol on the internal servers. There is some people here in the forum scared due to the fact that some servers have red crosses on port 443 and MSNP21 ports, but those servers are just offline for maintenance and that happens VERY often. Also you cannot trust blindly on the www.ismsndeadyet.com scanner because it can display errors sometimes due to packet loss, etc. It is even mentioned in the site.