i have android platform, if i upgrade to unity 4 will i still have the android platform 
If you upgrade also the Android licence.
Im guessing like me you got the Free Android / IOS offer with Unity 3.5 last April ? (Thanks Unity) . And I am staying on 3.5 until I can buy Unity 4 + the licences for Android / IOS .In a nutshell to use Android on Unity 4 you would have to purchase it ,but I am happy to stay on 3.5 until I can afford to buy 4 + licences ,(Money well spent IMHO) 