I don't think there should be any such rule.
There's no rule on the number of times a batsman can back away while facing up to a bowler. The umpire can warn him, can also penalise the team five runs if he thinks it's a case of deliberate time-wasting but there's no such rule that prevents him from backing away.
Same with the bowler missing his run-up or Mankading. If the umpire thinks it's a deliberate ploy, by all means penalise the team those five runs, but introducing a 'one unsuccessful Mankad' rule is only taking away from one of the forms of dismissals.
In any case, a fast bowler will end up tiring himself if he keeps running up and down just trying to 'Mankad'.
In this particular instance, it's a marginal call.
Assuming that age-old "line belongs to the umpire" rule holds true in this case as well, replays seem to suggest the bat was on the line when the stumps were first broken - at least that's what I think. Assuming this was a more typical run-out & not a Mankad, I would have been happy with the out decision. (I am happy with the Mankad too, just that I feel there could be a feeling around that because it's a Mankad, the batsman could be given bit of a benefit if the third umpire isn't too sure where the bat is).
There are many centres in India where Test cricket gets decent crowds. Bangalore, Chennai, Mumbai, Kolkata, Delhi are just some of them, so it's not very bad. Mohali and a couple of others don't have any watching Tests though and there's often a thought why afford them a Test anyway.
Generally speaking, however, it's T20s and ODIs which take precedence over Tests but I also know if it's cricket, it's willingly consumed by Indian TV audiences. So, the problem Tests face on lot of occasions is it's played during office hours as opposed to ODIs and T20Is which either start or stretch into the after-office.
What's very interesting is these days, there're people consuming a lot of non-IPL domestic cricket on TV too - Ranji Trophy and its List A version. So there's some hope there.