Well, the people who have the lion's share of bitcoin are satoshi and his friends.
Whomever they are.

If they re-enter the game, then speculation from the present becomes impossible.
It becomes a question of, what is their plans?

Barring that, lets say, 5... 10 years down the road, who will have the lion's share?

None of the above.

In the future, pensions won't exist.
In the future, banks won't exist.

That leaves private investors... and they will not be the holders of the lion's share.

Basically bitcoin will be used for settling huge debts, like

• trade balances between countries.
• buying containers full of stuff from china.
• inter-corporate debt settlement.

The thing is that the rich will buy-bid up bitcoin.
Fortunately, bitcoin is an honest money, so those rich won't be able to just use their money to make more money (by being part of the money-creation cycle)

So, basically people like the rots-children will start haemorrhaging money and in a few generations it will be all gone. But, for a while, they will probably be the lion's share holders of bitcoin.

The people will be using other coins.