The problem with Internet Explorer 6 was always that Microsoft stopped developing it after achieving dominance. Internet Explorer 6 was not a bad or outdated browser when it came out, it was quite modern for its time. It only became outdated once it was abandoned.
Google’s incentives aren’t set up such that they would benefit from abandoning their browser. Google wants people to do ever more stuff on the web. Abandoning Chrome would limit the stuff people can do online. Even in the unlikely event of Google achieving total dominance in the browser market, I don’t think their incentives are set up in a way that they would ever be interested in letting Chrome become outdated.
Oh sure, should they achieve total dominance Google might be tempted to do evil stuff with that dominance. Stopping developing Chrome, however, is not one of those things.
As such the situation is not even a little bit comparable. Google achieving total dominance in the browser market might still be bad, but not for the same reasons Internet Explorer 6’s dominance was bad.
Honestly, however, I think that this is mostly a fault of Mozilla, Apple and Microsoft sometimes not getting their shit together. You can’t really blame Google.