I was present for the perl4 to perl5 shift. It was pretty
fierce. Lots changed and there was a great wailing and
nashing of teeth. In the end, most of the old scripts continued
to work ( albeit with strange new warnings and errors ) and
there were many docs written to support you translating
your scripts from perl4 to perl5.
The downside of this is I know people who are still
saying they need to learn the new perl5 features and still
write their code as close to perl4 as they can.
Wait to see what happens. Experience says you
will not have to do it overnight - very few places will
immediately upgrade. Other experience says the perl6 developers
will try to keep a good balance between breaking needlessly
and breaking for the sake of real advances. Most things will
be depricated in perl 6.0, and will outright break on perl6.1.
mikfire