Have two wheeler annual sales in India come close to topping out?

Just been thinking about it. Two wheeler companies have had a great year. Their stocks have also performed well. 20%+ growth cannot be scoffed at for an industry which suffering everywhere else in the world. But to think of in a more macro point of view I was just trying to understand if this spurt was the last hurrah that these companies will have, in terms annual sales growth?
Just to make my point clear, I am not suggesting that their sales are going to collapse 50% tomorrow. All I am questioning is whether the long term growth of two-wheelers has reached an absolute mature stage, where low single digit growth or flat sales are the norm?
Here is my thinking process:
Just consider the Indian population 115 cr, roughly. Roughly 50% of those are females. Not exactly great potential customers for 2-Wheelers (2-w). Out of the remaining, 55 odd crores, 20% are probably too old to buy a new 2-wheeler (or past 2-w customers) and another 20% are too young to own one (future customers!!). Thus you are left with 35 odd crores as potential customers. Probably 10-15% out of these are our unfortunate brethren who are categorised below the poverty line and thus have very little to afford a vehicle. So we are left with around 25-30 cr potential customers. Out of this there will around 7-8 cr. people who already own a 2-w (total ownership of 2-w will probably around 9 cr.), and are not about to replace in a "given year" (year under consideration). That leaves us with a potential base of 20-25 cr serious customers.
The demographics will probably change in favour of the 15-35 age group going ahead. It has already started to happen in the last 5-6 years. But the change happens slowly and cannot possibly give a kick every year. It will help maintain sales, but growth is questionable.
This year we might sell around 8-9 mn 2-w. That means a conversion of around 4-5% of the customer base. That to seems a very reasonable conversion ratio for a big industry. A much bigger conversion ratio does not seem feasible simply because the sales will collapse too soon going ahead.
It is also difficult to quantify the effect of competition from 4-w given the aspirations of people. But since we cannot quantify it, we will leave it out of our calculations.
And I have also not discussed the effects of the huge 6th Pay Commission payouts and other stimulus measures taken by the government in the last 4 quarters. Again since I cannot quantify it, I will leave it out of the calculation.
All this makes me feel that 2-w industry in India is about to enter a phase that will give their investors a very hard time.
I have to say that it is not the highest conviction thoughts in my mind, but I am convinced enough to put it down in writing.
Lets wait for "TIME" to pass the judgement on this one!!