Will we (or our descendants) want to have same discussions for Perl 7, Perl 8, ...?

I would only expect that to happen if the proposed Perl 7/8/whatever is a ground-up redesign of the language which breaks backwards compatibility. (Yes, there are ways to run Perl 5 code in Perl 6, but the core P6 language is not backwards-compatible with the core P5 language.) Love it or hate it, Perl 6 is different enough from Perl 5 that even its biggest fans have taken to describing it as a "sister language" to Perl 5, or as "two languages in the same family", rather than as consecutive versions of the same language.

If, instead, it's a primarily-evolutionary change which allows you to run previous-version code using the next-version tools with few or no changes, then I would expect calling it <same name> <version++> to be just as uncontroversial as it is for every other piece of software out there.