If the housing needs replacement, it's likely that the tape would benefit from replacement regardless. It does not take long if you get good at it.

No way in hell I would ride a bike with DIY drilled handlebars down the block not to mention across the country.

On handlebars that do have factory internal routing (for integrated shifters) it would be difficult to replace the housing without removing the tape regardless--it always runs under the tape at least a little bit to the shifters because the shifters need some room to be adjusted. No such handlebars exist for bar end shifters so the point is moot.

For what it's worth the housing from the bar is the least likely to get contaminated. If you really hate wrapping your bars (and the tape doesn't look disgusting) you can probably save time (though not money) by replacing your cable at the first sign of friction, then replace the rest of the housing and the cable the next sign of friction, and then finally replace all the cables and housing, at which time you'll probably want to replace the brake housing. I'd just replace everything and retape every time, but I'm also a paid mechanic and can wrap bars in a couple minutes.