A man once said 160mm is the new black.
Black is pretty damn sweet - think about how good black is; it goes well with any jeans, it always looks cleaner than it is (well shirts do anyway, not black cars), its consistent and you very rarely see a shitty black. Well if 160mm is the new black I want mine blacker than your wives heart.
And rightfully so - its all good to love riding a hard tail, or sprinting across the flat cornered tracks that 100mm will devour - there is nothing wrong with that at all. But as a good friend of mine once said 'you can ride up anything 100mm will go up on 160mm; you may not be as fast as the 100mm but you will make it; now reverse that and try to ride down on 100mm vs 160mm...it doesn't handle it' and he is right.
Geometry has played a big role in that - shorter chain stays make it easier to be nimble on the larger travel bikes (thanks BMX), longer top tubes allow you to sit IN the bike rather than ON the bike, slacker head angles that can tighten up with travel adjust forks... technology gets better. We no longer need two bikes - the trainer and the weekend hill bomber. We can have one bike. One bike to work on and pay for, but most of all one bike to get comfortable on.
I am one of these people that is really funny about geometry and how the bike feels - I won't say the Slash was my favourite bike first few rides in; it took a bit of adjusting and playing with shock/fork settings, bar widths and rises, lever heights... I am a weirdo. But having one bike means I can tinker a lot more with settings, more ride time on one bike and that Zen Be At One With The Bike attitude comes into play. Now after some time (not too much money) I am feeling really comfortable on the bike - although I have lost some nerve thanks to silly little injuries.
I am no expert; but I can see a future where the geometry will play a bigger role than the travel. I think 160mm is too much of a bike for a lot of people - but thanks to the less twitchy and the sit in not on train of thought I can see 140mm (+/-) bikes getting the "ENDUROOOOOOO" treatment and slackening out - Transition have done this with their 120mm Scout and rumour has it these things ride like a mini downhill bike but climb like a ghoul from the grave. So a well placed geometry 140mm travel bike will go to new heights; bordering slopestyle AM hybrid with a higher bottom bracket and slightly more relaxed seat tube angle.
Don't be scared of evolution - just try not to buy too much into the hype based on hype. Ride what feels right and ultimately nothing else matters.
We could be still riding things like this - although the can can through the frame was the tits. 18 minutes it the Hammer is Dropped.