Perl/Tk will always be available, like an old grey workhorse. It may not have all the latest and greatest features, but it will be there, and it will work ( maybe with patches :-) ).

I kindof look at it like bicycles. Perl/Tk is that old single-speed coaster bike with puncture-proof tires, that sits in the garage, while you have more fun on that 21-speed mountain bike. But.....when that 21 speed derailer malfunctions and refuses to work right, you can always count on the old reliable single speed.