I doubt it. Bitcoin have disadvantage of relatively long block time (15 minutes), so there is IMHO room for at least one secondary coin with faster transactions (like 30 or 60 secs per block) that is more suited for quick microtransactions. Possibly even more coins if they bring something unique - more anonymous? conditional transactions? I think Bitcoin will sort of "replace" (or complements) bank accounts and bank transfers (or the business done thru these) and some secondary coins may replace micropayments like Paypal, etc ...
The bitcoin family though of coins that one can merged-mine all at once does already have a fast transactions member: GeistGeld.
However, GeistGeld is possibly too fast, at least one merged-mining pool dropped GeistGeld from its merge due to the speed of the blocks.
However the same merged mining family of coins also includes I0Coin and CoiLedCoin, I0Coin is I think maybe two and a half minute blocks or somesuch and CoiLedCoin one and a half minutes or maybe one minute or something like that and whatever their block speed is does not seem to be too fast to be practical, they seem to merge fine without screwing up the mining of all the other coins in the merge by requiring all the miners to get new work every 20 or 30 or 40 seconds. (I cannot recall offhand whether GeistGeld is 20, 30, or 40 seconds, whichever it is mmpool.bitparking.com claims it is just too darn fast to be practical.)
-MarkM-