The MKI is still (by some margin) the most capable fighter in that part of the world but the Rafale will displace it from that spot when it enters service.
I do not agree with this statement as this is the dilemma to US and other top 10 defense budget countries. Its not that who is better than the other than which roles are performed by which.
Su-30 MKI are agile and proficient in air superiority. This is their main role.
Dassualt Rafale is basically a multi-role fighter (jack of traits and master of none). Its mainly known for its air to ground role.
So even in war or any skirmish, the first step is denial of air space which will be handled by Su 30's and then followed by targeted ground attacks including destroying airstrip and arms cash followed by next objectives. They complement each other and are not meant to replace each other.
Currently for the air superiority role (commonly refereed to as dog-fighters), there are only F-14(retired), F-15, F-22, Su-27, Su-30, Su 35 are the most famous platforms.
France had never had a air superiority fighter and have always relied on other sources to projects its power including submersible, floating, UK, EU and NATO (last 3 are political).
Now lets jump to the first line of my conversation about dilemma. The issue is that US had exported F15's (ASR) and F16(MR)'s to its allies previously. Now with F22 (ASR) they has put a ban on the export of arms and technology and are only offering F35's which are for air to ground, interceptor and bombing support missions.
Just to troll a little, while french compare Rafale to Eurofighter and show their admiration. I usually think of WWII when french were holding the trenches and asking British(at that time) to save them.