I think the influx of new users is good; there are probably people out there with great things to contribute, that don't even know Hacker News exists. But of course the characteristics of the front page posts are going to change.
There is a somewhat controversial solution here... just make a sub-section of HN where only users that signed up X days ago or earlier can post and vote. If X = 250 and guys like me get screwed, then so be it; if old timers are actually better voters, then at least I'll get to read the better articles. And you don't lock out new users either, since the original front page will still exist without any vote weighting.
Personally I don't know if the quality of the "old timers" section would be any better or worse than the normal front page, since "interesting" is a subjective concept. But if you miss the Hacker News of the good old days, then maybe it makes sense to bring that HN back to the future this way.