I think you are shortchanging the London shooting contingent a bit.
Vijay returned with a silver medal and Joydeep came extremely close, besides Gagan's bronze of course. Even AB had a weak final round of qualification and missed out, else he was on course for final after 5 rounds. Heena was not too far from the final, finishing 12th. Of course, we all remember the heart-break of Ronjan.
Fact is shooting is a highly unpredictable sport and anything can happen on the day. Even the contingent of London had world cup medals to show as does the contingent at Rio. Its just that we know our shooters better this time than we did at Rio as we have all been following the qualification process closely.
And AP, AC, Gurpreet, even Chain, have unfortunately been a bit disappointing of late. Though, yes, we never had a Jitu Rai at London. He is in a class of his own (but also untested against Olympic pressure which really is a beast of its own).
So I'd say the contingent is a little better but don't think it is a massive improvement. I think we'll still probably end up with 2 medals, may be 3 (and I'll be heavily disappointed but not exactly surprised if it drops to 1, just due to the sheer unpredictability of the sport). Hopefully, at least one of them will be GOLD.
As for Saina, it is definitely a different situation. At London, she was heavily favored to reach the semis but was the definite underdog from there on. This time, no one is really unbeatable but it is also a much wider field.
But, she went into the London Olympics having won 3 superseries titles and with recent victories over Xuerui and Shixian (who didnt make the olympics, but still..). Also, Wang Xin was on the wane. Personally, I was seriously hoping in London that she avoids Yihan in the semis in which case she would likely have a shot against both the other Chinese and I expected her to come through at least one of them.
This time, its been a while since she beat Marin or Xuerui. She also has a bogey player in Tai though hopefully that wont come into play. Had she not won the Australian super series, I would have no doubt in saying that she was better placed in London. But with that victory, it is much more even. She definitely has a better chance of GOLD this time than she had last time, but the chance of reaching semis and sneaking a BRONZE was probably still a tad higher last time.