With Bitcoin as it is right now, I very much doubt we'll see $2000 by end of 2015. The spike we experienced last year was the result of hype + panic buying and because it was the first real 'rocket to the moon'. A lot of people made good money but a much greater number of people lost money. I think people are gonna be a lot more cautious now before going 'all in'. There is also a number of smaller factors that are different now. For example, the altcoin scene has exploded since last year and a lot of people are tempted to invest in altcoins because that's where a lot of new tech is emerging. The price of Bitcoin is already quite high and a lot of the smaller guys might think twice before buying BTC just to hold for better times.
On top of that, we've had a few scares since last year. Gox turning out to be a scam and losing people millions but more importantly, mining groups that have nearly compromised the whole network by being in control of close to 51% of the hashrate. This last one can be pretty scary for big investors because there are no laws to stop someone from taking over the network.
I think BTC price can still go up, maybe up to twice its current value but without improvement to the system itself, I don't see major investors pumping millions into Bitcoin anytime soon.
Last year was not the first big rally, we had similar rallies before!
The price per BTC is a function of Demand and Supply which is related to the expected value of all Bitcoins in the future. If in 2015 the market thinks there is 30% chance that the price is 30000$ in 10years we will easily have 3000$ per BTC.
Regarding the first part of your comment, my bad, I wasn't clear enough, the 'spike' I'm referring to is the one between end of Oct 13 and beginning of Dec 13. We've never had anything on that scale prior to that.
Concerning the second part, my comment actually explores some of those factors that affect 'demand' directly. As much as I would love to have BTC reach $3000 next year, I don't think it's very likely to happen