It is very hard to put an amount that I could potentially earn being part of a small indie development team, many factors will affect the revenue from the games we will create : team size, licenses, software, distribution, publishing and how well the game actually performs.
I recently looked in to forums where people were attempting to setup their own indie companies to no success, people had individually released games but without the correct marketing and deployment knowledge to gain enough 'hype' or attention to cause a snowball effect of downloads. An example is a forum user reporting after having his game on the market for over six months, only receiving $1.37 in total from Kongregate.
There seems to be split opinion on what makes up a successful indie game, many people argue that indie games can push the boundaries of the industry and thats what makes them appealing to gamers. Other people suggest that being innovative is not enough, and for the game to 'make it' it needs to have up-to-date graphics and replicated much of AAA titles with a team not even 10% of the size.
It appears much of the research I could do particularly on iOS/Android market platforms would just lead to 'clone games' where a particular game mechanic which proved popular has been replicated and slightly modified/reskinned by small indie studios in hope of cashing in on a quick buck. (see Angrybirds, Plants Vs Zombies etc).
It almost seems impossible to work out any figures to what a studio could be expected to earn, with games such as Temple Run which sees 13 million people play their iOS/Android game each day and the introduction of in-game purchases being a major part in Imangi Studio's sequel Temple Run 2.
The market is constantly shifting - with mobile devices ever increasing (more users) the more apps saturate the market (less visibility for developers), the new push on independent studios to produce games for the PS4 and XBLA, Unity and UDK becoming more popular and accessible and the ever mounting spotlight on indie devs releasing titles in succession to previous games that made a major impact on the gaming market itself.
