Simon won't sack Louis. They are close friends and business associates. Louis is there for a reason and is bombproof.

Dannii has very little effect on the ratings.

ummmm and you know that how? Dannii is better than all three of the judges put together and now i'm beginning to think the sooner she gets out the better. the show is gonna be bland and boring as hell with cheryl, simon and louis because it's not like cheryl is outspoken and out of the box like sharon. I guarantee that simon would miss Dannii if she were to leave even though they may not look like the best of friends! and i could see him asking her back!!

I think the only judge that has a big effect on the ratings is Simon.

Cheryl may have a little effect, Dannii perhaps a little too, but whether they'd go up or down if they left depends on who would replace them.

If we look at the ratings averages over the audition shows (this way increases/decreaes can't be put down to the choice finalists like in the live shows and judges houses)

Overnights:
XF1: 6.6m
XF2: 8.2m
XF3: 8.1m
XF4: 8.7m - Dannii Joins, 600k increase
XF5: 9.9m - Cheryl Joins/Sharon leaves, 1.2m increase
XF6: 10.3m - Introduction of audition audience

So both of them appear to have increased ratings, however not to the point where they aren't replaceable

Or it can just be attributed to people growing up. Someone who was five when XF1 was on is now eleven, so more than likely going to be watching X-Factor on a Saturday night. The people who have loyally watched it for about six years aren't going to be going anywhere, whether they say they will boycott or not. So X-Factor does better as each year, there are just more and more kids who are growing up and watching it. That's probably a more likely theory than a million people tuning in just to see Dannii Minogue.

I don't think it's fair for you to say that Cheryl and Dannii are the reasons why ratings increased in the years that they joined (and this is coming from a Dannii fan). Ratings for shows like this tend to grow year on year, as they gain more reputation, more advertising and become more established. 1.2 million people didn't JUST tune in because Cheryl was there, and Sharon was gone; similarly, you can't say 300k people solely tuned in because Dannii was joining the panel.

Going back to the OP, i would love to see Dannii join USXF, but know this is highly unlikely

Dannii for the US

I'm not saying it was because of them, no one can say that, however I am suggesting that SOME of extra viewers could be because of the judges,

A1.2m increase in ratings from 2007-2008, especially after a crap winner (Leon who?), is not simply down to becoming more established. Look at series 2-3, the ratings fell.

The only thing that changed from 2007-08 were the judges, with Sharon leaving and Cheryl joining. Obviously not every single one of those extra 1.2m viewers tuned into because of Cheryl, but I expect quite a few did. Same with the 600k increase when Dannii joined.

This year with even more advertising and the show being even more established, even with a new format, the ratings didn't increase as much as previous years when new juges entered.

I think Dannii would do very well on XF USA - she has the judge experience (have heard her say that she gets very close to her contestants), and she is qualified enough.

Otherwise, my line up would be:
Simon
Dannii
Kelly Rowland/ Queen Latifah
Jay-Z (we live in hope )

And Dannii is outspoken and out of the box like Sharon?!

She'd actually have more chance of getting the job in the US if she and Simon hated each other. When Sharon got the job, she and Simon had recently been embroiled in a very public feud. That's why she got the job. The problem is that Simon and Dannii do not interact much. The X Factor format is based on conflict and they'll play that up when it goes to the US. For that, the judges need to bicker with each other. They need to make comments that outrage the other mentors. That's not Dannii.

Tbh, Sharon has more chance of landing the job than any of the UK judges. But I think they'll look for someone younger.

But hey, maybe if Simon Fuller see's all these DS polls which show how great Dannii is, then he'll hire her as the new head judge on American Idol?