If the new SSKs Song class, Yuan class and the improved Yuan come close to Kilo in stealth then you can say we are effectively outclassed in this department.
If they match the Kilos then you can say they are equivalent or even superior to PN's Agosta subs as well. They should be a match for the Scorpenes IN is procuring. Without AIP, the tactical advantage is lost to us.
The Americans claimed their older Song class is an equivalent to the Kilo. They hold the Kilo class in the highest esteem for it's capabilities.
Without the Project 75A tender happening quickly, we are effectively screwed in this area. Our immediate plans call for 1 Akula class sub and 6 Scorpenes by 2020. Who knows how many China will build in the mean time.
Dear P2Prada: basically I agree with your comments, and I do read that Americans article (an Office of Naval Intelligence, actually). Just some add-on:
the ONI is appraising the "stealth" capability (i.e. silence), but NOT 2nd, 3rd, and 4th important key factors in sub warfare: sensor, combat system, and torpedo.
China is good in hiding all the data, so we may only be able to guess:
Yuan class is the first one in China (or second, to 093 "Shang" class SSN) equipped with hull-mounted array sonar, which is ~20 years behind western & US. It's yet known how good PLAN learn to make best of this new equipment. And this come to next factor: your combat system (computer) --
First you will have to learn how is best to use that sonar, then you can design your combat system and correctly use it accordingly.
Torpedo is another notorious weakness for PLAN. Although the constraint for 092 is old story, last few years PLAN acquire quite many Russian and even US torpedos. All the Yu-6 and Yu-7 torpedo are all reverse engineering. Now, unlike many people, I do hold high score toward China's rev-engineering capability. Many their works are actually brilliant. Yet, this one we again can not give enough details (ONI paper also admit it).
In a sub warfare, the best tactic is still
i) quietly sneak so close to your foe (silence), so that
ii) you are 200% sure (sensor)
iii) they can not get away your weapon (torpedo)
And if you have to face more than one enemy submarine, the combat system is even more critical as you need it to analyze all the signals, threat assessment, tracking (even has to track fired torpedos)
All I am trying to say is there are still some more details to say China's sub strength is really that superior to India once 75A delivered...