Biggest problem is not many people have any sort Bitcoin earnings, that's currently the biggest obstacle in BTC adoption and it's use as currency.
If the offer of services in
BTC will result cheaper or faster or better in
BTC, than with other currencies or payment options, people will goes to exchangers to buy
BTC.
And if people goes to buy or earn
BTC to store - this is against
BTC diffusion.
There will always be people willing to sell, there is not a problem of lack of diffusion of BTC... the price will just go higher if there is demand, and since BTC can be divided as much as we wasn't there is not a problem of liquidity possible in any case.