Didn't it get addressed since the old proposal before the recent 8 MB one, mand ?
I dunno. I can barely keep up with it all.
China's expressed interest in 8mb blocks but not the doubling every two years that Gavin Andresen proposed.
Here's a quote from the XT github 'Please note that Bitcoin XT does not currently change anything about block size limits, although a future version might.'
Someone cleverer than me will be along to clarify eventually.