I would think that if your cable is kinked, it's not going to turn so I'd take it out. I don't know, but I'd expect the gears to go before the cable does. Taking the speedo cabled out shouldn't cause the gears to drop off. The risk is that they get shredded. I'm not sure if age is the only thing that causes their demise. I suspect that drag from the cable may aggravate the problem. In any case, if they go, the tranny has to come apart.
This got me wondering how much of a problem it really is and if my memory that several other owners had reported their gears going was accurate. I don't want to cause anybody to go through a lot of trouble and/or money to fix something that probably won't break. I did a search on the online Knowledgebase looking for postings from people who's gears shredded but I didn't see any (that's not necessarily the whole story as all the lotuseuropa group posts may not be in the knowledgebase yet), but I did find a few threads about replacement gears and having new ones made. If you're concerned, you might want to email Steve Veris (steve.veris@sbcglobal.net). I believe he had some speedo gears made and he probably has better information about this than I. I do know that mine did shred in my NG3.