Question about XHTML 2.0 and content type

Will XHTML 2.0 *have* to be sent as "application/xhtml+xml" (or one of 
the other XML content types) or will it be allowed to be sent as 
"text/html"?

The main reason I'm asking this, is because after doing some tests I 
realized that Google Adsense will not display on any page sending out 
"application/xhtml+xml" as the content type.  Which would mean loss of 
revune.

I'm very interested in using XHTML 2.0 when it is finished and a doctype 
is made for it, but I'd prefer to use "text/html" if I can.

So just wondering if the rules will be the same as XHTML 1.0 in which 
it's allowed for websites to send the document as "text/html" as long as 
certain compatibility guidelines are followed.  Or if the rules will be 
the same as XHTML 1.1 in which "text/html" is in violation of the 
specification, and you can only use "application/xhtml+xml" as the 
content type.