Nope kalki avtar will not arrive soon(at least not  in 2012), but at the same it is entirely wrong that it will take  thousand of years to complete ,the biggest problem with Hindus is that  they take everything literally . 
According to scriptures kalyug is the shortest of all yug . 
Yuga Time Period 
Kritha Yuga 17,28,000 years 
Tretha Yuga 12,96,000 years 
Dwapara Yuga 8,64,000 years 
Kali Yuga 4,32,000 years 
that means difference between dwapar(krishna) and tretha(ram) should  exceed 432000  
but due to dating process and other astronomical figures some say ram  was born in 7000 bc to some in 10000 bc while some say krishna 's birth  took place somewhere in 3000 BC TO 1500 bc it maximum is to be take the  gap should be not more than 7000 years , therefore kaliyug should have  period of 3500 years now we don't know when did  
kaliyug start if 1500 bc(which most historians believe) then  1500+2000=3500 years that mean it should take place somwehre in this  century or definitely in next century . The duration of years in hindu scriptures is surely different from the current span of years 
  
I am saying kalki will not born in 2012 bcoz many things are left which  are progressing fast and could take place only after atleast after 2 or 3  generations.The prophecies in Mahabharat and bhagvad which have not  been attained so far are written below. 
  
1) puberty of girls will reach to 5 and 6 (mentioned as prophecy)  ,puberty of gals declining fast , declined from 14 to 10 present ,  it would take few generations or decades to reach up to 5 , the  same is  for  boys it should reach to 7 or 8 it is 12 currently , I suppose in India. 
  
2) maximum life of human beings will be 16 years (medical facilities  have elongated human life ) so I don't know when this will happen 
  
3) There will be very less of people and seven suns will shine , this  reflects III world war , after that only population could reduce and may  be due to the aftermaths life span will reach to 16 years. 
  
4) Land will become barren even the plains beside rivers will not yield  and ppl will eat roots and drink goat's milk , this too indicates some  sort of nuclear war  
  
5)Kalki will fight with buddh people and the villain has name Jin ,  China is the only country where Buddhists are found though no religion  is allowed due to communism , yet China has large amount of Buddhist  people , and Jin sounds like chinese name,. It seems new world order  will be formed wiping out America n other western powers . After  recession many experts believe there will be second recession in western  countries within a decade and China will emerge as the new superpower. 
  
All the above points relfect that there would be a war prior to kalki's  birth and evil powers will win , and bhagwan will wipe out the evil  powers then