I wouldn't call 2999 near. I'm almost at 2040 in my current game, and I feel like I have played it for ages (since 1850 or so). It's hardly any fun anymore, as there are no new vehicles, except a few that are so badly balanced that they won't generate a profit no matter what. Cities are so huge, covering them with local transportation, let alone coming up with names for the stops, is tiresome. I mostly just sit and watch the trains run. Sometimes I try to reduce the losses that set it on my rail network due to a skyrocketing speed bonus base speed around 2030, but almost nothing works.
Generally speaking, changing the default could potentially cause compatibility issues. Perhaps not so much for the default retire date as for the default introduction date, but still. If a pak set is ready for a longer timeline, it should go for it itself.