You aren't alone. Check out RFC 28. I've been reading the p6-language list, too, and the impression I've been getting is that most people largely agree with you that the language shouldn't be changed as much as extended. Deprecated uses aside, I expect very few well-written scripts scripts will break during the transition, since there's such a huge population of functional scripts out there which the Perl 6 developers can't afford to break for the sake of cleaning up the source.

That being true, you won't have to learn anything new if you don't want to. But that's true now: very few Perl users know everything about p5 that there is to know. That's one of the great things about Perl: it's learning curve is as steep as you want it to be.

No matter what, your concern is premature. Until v6 has been proven as a solid platform, there will still be community support for the 5 series. The rough timetables I've seen project completion within about 1 1/2 years, but getting through the bugs for a full overhaul will require some time more. So you can keep using Perl for at least that long without needing to learn a thing.

Overall, I don't think anyone is going to lose out during the change. There are a lot of good reasons for reimplementing the interpreter, but the language designers seem determined to keep it accessible to its current fans and new users alike.