Until one full bitcoin is priced out of the reach of most folks, other alt-coins, including quark, won't fly too high. It's not a problem though, it's because who is the first always gets the best piece of the pie. Bitcoin is already starting being priced out of the reach of many.

Oh, and also, when bitcoin network can't handle all the transactions (which is only 7 times more transactions than it handles now) and/or fees on bitcoin transactions become too high dollar-wise, then other alts will come to rescue, including quark. When will that happen? Hard to tell, depends on the adoption rate by merchants and businesses.