Is it possible to develop a great kick later in "life"?

Yes it is. You have to start but if you focus on it it can be great... I've improved mine and I think it's pretty good now, and I know I can get it better.

Here's the kick improvement program I've developed & shared in the "Help! My Flutter kick is Horrible" Thread Anything you do & measure, IMPROVES so start doing & measuring the right stuff.As testimony, being a 44 year old (non swimmer 42 of those years) who couldn't kick worth a crap 7.5 months ago and times were proof of this, this method can transform your freestyle speed considerably.

I believe an efficient kick is more important that a strong kick. Developing a strong kick just for the case of a strong kick needs to be balanced against what it might take away from your stroke overall. Then again, don't listen to me, kicking is for the birds. Geek only knows what kicking is when he sees Fort go flying by him in the 50 or 100 back.

You can at least improve your kick significantly, but I am not sure everyone can be a great kicker. I disagree with "difficult to develop a great kick if #1 - you didn't start young". What this really means is developing a strong kick, if you don't naturally have one, is hard work, and hopefully you have already done the hard work :) I think kick has as much technique involved as pull, but you don't have the same fine motor control in your feet that you have in your hands (or you would be a soccer player not a swimmer), and you can't watch your kick. This retards the learning process, and learning to kick well is a lot of time consuming experimentation. You have a great plan for improving your kick. My kick is faster as a master than it was as a kid, and what has helped me the most is kicking fast. Instead of worrying about finishing the kick sets like when I was a kid, I have no problem doing 25s with lots of rest FAST and not worrying about what the set actually is. I learned to kick fast (for me) first, before I went back to longer kick sets. I think this is important. Ande's suggestions to kick all out with lots of rest was what put me on the right track to improve my kick.

Good point, and this is especially true for triathletes, I would think. The one thing you don't want to do in that first leg of the triathlon is burn out your legs. I imagine you would want a 2-beat kick for most of the OW swim in a triathlon, though a more vigorous 6-beat kick might be good early on to get to clear water. I think that the key will be to develop ankle flexibility. Increasing it just a little bit makes a huge difference in forward propulsion for the same kicking effort. Many lifelong runners (and others who didn't swim when young) have pretty poor ankle flexibility which might be the cause of statement #1 in the OP. On the other hand, not being a runner, I have no idea how developing better ankle flexibility will impact one's running (especially susceptibility to injuries such as turning an ankle). I am a runner - and have poor ankle flexibility :) My coach wants to develop the 6-beat first and then work on the 2-beat when I become more powerful. Triathletes or not - the best swimmers have a good strong kick. Some 2-beat and some 6-beat. The coach I have is also a triathlete (and ex-college swimmer) and he has a powerful 2-beat kick... and he is usually first out of the water.

I believe an efficient kick is more important that a strong kick. Developing a strong kick just for the case of a strong kick needs to be balanced against what it might take away from your stroke overall. Then again, don't listen to me, kicking is for the birds. I've noticed the best flyers and backstrokers are strong kickers. It might be the underwaters. You can have a weak (but efficient) kick and be a top freestyler though. See: Janet Evans. Maybe less so with sprinting, but hey, I'm a terrible kicker and the 50 is my best event.

Ditch the kickboard.I don't think traditional kick sets with kick boards are going to do you a lot of good for improving your kick as the board puts your body in a very different position than when you're swimming. I prefer kicking on my sides, hands at my hips, head facing down, switching sides either in the lap (to work on body roll as well) or for each lap. This drill has a number of added benefits beyond kicking -- head position, body roll, learning to swim on your side. Work your body rotation. I have no clue how you swim, but I see way too many triathletes swim "flat" in the water. I grew up as a solid, 2-beat kicker as a fairly decent distance swimmer, but my kick for my events was less about propelling me forward and more about propelling my body rotation around the long axis. If you can think of your 2 beat kick as initiating the body roll, you'll end up getting decent kick propulsion, but more likely end up with longer distance-per-stroke and will slice through the water better. Don't use pull buoys. Again, I see lots of triathletes resort to doing a lot of pulling sets with buoys. That's great if you want to build your arms, but I think they are detrimental to a fully-connected freestyle. They train your body not to learn the muscle / coordination connections between pull and kick. Plus, I think they generally make people swim flatter in the water. Totally agree with pwb. I ditched a kickboard several months ago. All my kicking has been either on my back or on my side, with the bottom arm extended. Benefiits: My balance in the water is better. My conditioning has gotten better. I am kicking faster now that anytime I can remember. My backstroke kicking has improved greatly, which has translated into faster backstroke swimming. If you feel the need to "pull" use a band around the ankles instead of a buoy between the thighs. The band will still allow you to rotate, plus you will have to improve your balance in the water or your legs will be dragged down.