GNUPG symmetric encryption compatibility question

[Robert J. Hansen]

> If I symmetric encrypt many files with the recent version of GNUPG 
> 1.4.19, will I able to decrypt these files with the modern versions
> of GPG in the far future?

Most likely.  The spec is well-known and unlikely to change in ways that
break backwards compatibility.  Over the next, say, ten years I'd expect
you to have no trouble at all.