I think I'd definitely replace it before taking off on a tour or long ride through the boondocks. I'm sure that their mileage estimate on belt life is conservative - the point is that they are asking you to replace the belt before it is likely to fail and cause a problem. If it did fail and leave me stranded, I'd have no one to blame but myself. If you want to chance riding locally with it - that's up to you, and you probably could get many more miles out of it.
The other consideration is that the way these dealers stock parts (LOL), your dealer is unlikely to have one sitting on the shelf when you need it. I'd recommend ordering & buying the replacement belt now anyway, so that you have it on hand when you do need it. Is replacement something you could do at the roadside if the belt fails? If so, I'd maybe carry the replacement belt in the trunk along with any extra tool(s) needed to do the job.
Just my 2 cents. (I'm not a big fan of getting stranded - I'd rather invest in preventive maintenance.)