Given how bad I am at predictions I'd like to give you the following (which you'd better take with a grain of salt): Python is the new Tcl and Ruby is the new Perl. My prediction for 2006 is that most Perl 5 programmers will decide that Ruby looks cool and learn the language and that Python will be a niche language that a die hard core continues to love and embellish.
I think Ruby's the new Perl because of the confluence of three things: Perl 6, RubyGems and Ruby's own Perliness. Firstly, given how hideous Perl is if you're a Perl person (like me) why learn Perl 6 when you could learn Ruby? Ruby's core language is clean, regular expressions are strong and there are many Perl influences (which Ruby is slowly removing to ensure that language doesn't become Perl). Secondly, RubyGems will do for Ruby what CPAN did for Perl.
Python's lack of good package management (if you ignore ActiveState's PyPPM and the recently started Cheese Shop) and idiosyncratic language constraints ("hey we liked signficant white space in Make so much we used it ourselves") make it look like Tcl to me. And where's the killer app? Arguably dynamic web pages were Perl's killer app, and perhaps Rails is Ruby's. Python has... Zope?
All of which leaves me wondering how to complete "PHP is the new..."
(Naturally LISP is the new LISP).