" ... am I doing to be able to find people with sufficient skill, and at a reasonable rate, to maintain and extend the product?"
That's an easier Yes if you're dealing with Java, C#, and maybe PHP and Rails.
What makes you think that?
Perl programmers are not that rare, nor --I think-- that expensive.
It is not because there are more Java/C#/PHP/Rails programmers that it will be any less painful to find someone willing to maitain an "inherited" codebase.
A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James