According to the press release from
Canon USA and
Canon UK the 1DX replaces both the 1D4 and 1Ds3.
The 1-Series primary market is the photo news agencies like AP, Reuters, EPA, SI and other related outfits. Everyone else is essentially secondary.
Because of the hypercompetitive nature of the news business upgrades are done often.
Businesses who find the 1-Series beyond their budget have the option of the 5 or 7 Series bodies.
The upgrade cycles I have mentioned earlier are verifiable and factual. All counterpoints I have read so far are solely based on rumors published on CR.

Yes, CR's posts are somewhat accurate but only for those products & services that were released within 24-48 hours after the rumor has been published. Once that lapses the rumor is just talk for gearheads to ramble about.
It is easy to be put on record when using a handle or pseudonym.

In terms of sales volume the 1-Series represents 1% of all EOS bodies made. So the pricing and features are for the 1%.
Anyhow, I am just rumormongering on inanimate objects. Those who are looking to upgrade like myself should take my posts into consideration if they want the latest and greatest.
What I hate most is buying really expensive gear then in less than 6 months a replacement will be announced to be shipped to your door step 3 months later.
Below are the product announcement pages from DPReview of all the 1D body generations.
EOS-1D X
http://www.dpreview.com/news/2011/10/18/canoneos1dx17 months as of today
EOS-1D Mark IV
http://www.dpreview.com/news/2009/10/20/canon1d424 months before replacement
EOS-1D Mark III
http://www.dpreview.com/news/2007/2/22/canoneos1dmarkiii32 months before replacement
EOS-1D Mark II N
http://www.dpreview.com/news/2005/8/22/canoneos1dmkiin16 months before replacement
EOS-1D Mark II
http://www.dpreview.com/news/2004/1/29/canoneos1dmkii28 months before replacement
EOS-1D
http://www.dpreview.com/news/2001/9/26/canoneos1dBelow are the product announcement pages from DPReview of all the 1Ds body generations. As earlier mentioned the 1D X is the successor of the 1Ds Mark III per Canon USA and UK press release.
EOS-1D X
http://www.dpreview.com/news/2011/10/18/canoneos1dx50 months before replacement
EOS-1Ds Mark III
http://www.dpreview.com/news/2007/8/20/canoneos1dsmarkiii35 months before replacement
EOS-1Ds Mark II
http://www.dpreview.com/news/2004/9/21/canoneos1dsmkii24 months before replacement
EOS-1Ds
http://www.dpreview.com/news/2002/9/23/canoneos1dsBased on the above product cycle duration here are the possible product announce dates if we were to start from October 2011.
16 months - February 2013
24 months - October 2013
28 months - February 2014
32 months - June 2014
35 months - September 2014
50 months - December 2015
And to repeat pro bodies and pro lenses are often announced before major sporting events. There are two scheduled namely Winter Games on February 2014 and World Cup on June 2014.
Based on the data provided I expect at least one pro body to be announced as late as October 2013.
I further speculate that at least a total of 5 lenses will be announced/shipped this year. 3 non-L EF lens and 2 L lenses. No data on EFS or EFM lenses.
Possible candidates for upgrades are below.
1991 - TS-E45mm f/2.8
1991 - TS-E90mm f/2.8
1998 - EF 35mm f/1.4L USM
2003 - EF17-40mm f/4L USM
2004 - EF28-300mm f/3.5-5.6L IS USM
1996 - EF 135mm f/2L USM
1998 - EF100-400mm f/4.5-5.6L IS USM
1993 - EF 400mm f/5.6L USM
A EF 14-24mm f/2.8L USM is possible based on patent filings and Nikon having an equivalent that is selling well.