So this could be the end of the bitcoin bubbles, possibly. Will a competitor come and dethrone bitcoin? Or, are we just entering a new and much smaller growth period?
This may depend on how the question of the 1 MB max blocksize limit is handled. One thing is certain without an increase in this limit,
and a hark fork is necessary for this, Bitcoin will be dethroned by a competitor. Once the limit is reached transaction fees will skyrocket as an ever growing number of transactions compete for the 1 MB space every 10 min. Fortunately Gavin Andresen understands the need for this. So do other Bitcoin developers. The real question in my mind is will they muster the necessary community consensus to make this hard fork happen?
I don't think there's any plausible scenario in which the death of Bitcoin is somehow an opportunity for some altcoin to take its place. The death of Bitcoin would be the death of cryptocurrency.