...it will be because of something elemental.
To blog effectively, one has to READ and LINK to other blogs. More and more of those blogs are composed by people who think that the entire freaking world works with a 16:9 ratio computer screen.
Mine is still 5:4, and I resent like HELL having to scroll left and right to read blogs that are specifically formatted for 16:9 screens.
If YOU write a blog, use a 5:4 template/format. There will be some blank area on the sides for those with 16:9 screens, but so farging what? It's still readable to everyone without scrolling side-to-side.
If you format up to 16:9, you are oh, so, modern, grass does NOT grow under your feet, and your Rolling Stone gathers no moss, but you are still an insensitive blogger who might get struck from my blogroll.
My next little research project will be to group my blogroll by who formats in the universal 5:4, and who kisses off 5:4.
I'm going to hazard a guess right now that the really solid citizens of the blogosphere use 5:4, not 16:9.
BTW, I am NOT going to buy a new computer just so I can keep up with the Joneses bloggers who like widescreen, nor am I going to reformat my laptop's screen so that it letterboxes everything. I'm 65 farging years old, am one of the few actually computer-savvy people of my age group, and I have a completely functional 6-year old laptop, with enough spares to keep it going as long as MicroSquish doesn't abandon XP (and when they do, I'll probably dump MS and go with a Unix-based OS).
Frankly, the only use I can see for 16:9 is to watch movies which are formatted in letterbox. The Western mind is trained to read material in some sort of column format, and 16:9 hardly counts as a column, and it presents text lines that are just too long to properly hold one's attention. 5:4 was invented for a very good reason, and while the eye may appreciate video in 16:9, it does NOT appreciate text in 16:9
You bloggers out there who give a shit about your readers getting the most out of your screed will present that screed in 5:4, and the rest of you can take a flying leap at a rolling donut.
I feel SOOOOOO much better now.