I read this post from Jeff Schewe (He Who Should Know).
… the upgrade policy has changed so that you can only upgrade to a new version from 1 version back. So, if you want Photoshop CS6, you need to be on Photoshop CS5. To get Photoshop CS7 when it comes out, you'll only be able to upgrade from version CS6.
The concession from Adobe to CS4 owners to upgrade to CS6 ended on December 31st. Does this mean that, when CS7 comes out, CS5 owners will be caught out and have to pay the full price for CS7 ? I just remember the scramble when some Adobe Person announced in 2011 that "the next upgrade to Photoshop CS6, to be released in 2012, only owners of CS5 will qualify, owners of previous versions of Photoshop will have to pay the full price".If this is correct, and Adobe don't relent as previously, CS5 owners will need to upgrade soon to "avoid disappointment" when CS7 comes out.
This will include me. But I can't say I'm excited about CS6. I might have been excited had I not felt forced in 2011 to upgrade to CS5 from CS4 in order not to allegedly miss out on the upgrade path.