i think that bitcoin has two possibilities in two years roadmap:
a) value near around 3000-7000$
b) value between 0 and 100$
..and what will be? nobody knows
I pick a) but hard to believe Bitcoin would not reach $10,000 before stabilizing at $3,000-$7,000 within two years
i also think that second altcoin will be litecon... becaue bitecoin has one disadvantage - is not fast. i cant imagine the situation, that in restaurant i will pay with btc and then wait to 3 confirmations. this is the weakness of btc. so in my opinion is btc "gold" (fast and small transactions is not necessary) and litecon "silver"
next question is - what value would have usd in two years? inflation....
First of all you don't need 6 or 3 confirmations. Those are arbitrary numbers. 99.9% of time you 'll be fine with 1 especially for low amounts like a restaurant bill.
In any case for pos like starbacks even 0 confirmations will do the job. Of course some kids will try to take advantage and order a coffee and then double spend but it isn't worth the trouble anyway
While it may not be worth the trouble to you or me, I think to greedy corporations that don't want to incur any losses it might be a bigger deal which is why I'm not looking away from litecoins. That said tho, while we all would like btc to reach sky high levels, I don't see it going much higher than 2500-5000 in the next few years. then again I could be totally wrong tho since back in april I thought it would never go higher that 200$ lol