Roughly speaking, "will TIMTOWTDI apply to the language itself indefinitely?" = yes.
Perl 5 is a language defined by an implementation, Perl 6 is a language defined by a syntax and documentation. While there's no predicting what will happen, as of now it looks like there will be a few implementations of Perl 6- there's more than one now and nothing to stop anyone with a good idea from starting another. On the other hand, there are a few implementations that have already gone into hibernation.