If you examine how temperature sensors have changed over time, what you'll mostly see is that the underlying principles of operation of the sensors haven't changed, but that the size, supporting electronics, packaging, and integration of the devices have all become more sophisticated. And this effect holds for pretty much every type of sensor that I can think of. Visiting trade shows like Sensors Expo brings this progression very much to mind.
A modern photoelectric sensor works the same way today as a similar sensor from a decade ago, but is now smaller, better, and more reliable (unless you need it to be larger, in which case it is larger, better, and more reliable). Inductive proximity sensors? Those can now sense multiple metals and have longer sensing ranges. Vibration sensors? Pick a desired bandwidth and you can probably find a device to fit. Pressure sensors? There's a wealth of choice based on pressure range, desired output signal, and desired operational environment. Name any type of sensor and if you compare it to an older version I'll bet you'll find that the new one is smaller, faster, smarter, and more capable.
Heck, take a look at data acquisition and industrial networking! The sheer variety of data acquisition equipment available is staggering and the combination of lower cost and greater functionality makes it accessible to a much wider audience. If you're trying to network an industrial facility you've got more choices than you've ever had before.
Something of the same process is happening with MEMS-based sensors, too. Compare a MEMS accelerometer from five years ago to one of the current crop and you'll find the newer versions have things like programmable measurement ranges, integrated self-diagnostics, a wealth of signal conditioning and communication goodies, and a size that'll make your head hurt. I expect MEMS gyros are the next MEMS sensors that'll snag the spotlight as they're improved and incorporated into mobile devices and go through the same improvement experience. (Also, don't be surprised to see multiple types of sensors built into a single chip. Some already exist but more will come.)
I find it immensely heartening to find that, as mature as some of the sensing technologies are, some bright spark always seems to figure out some way to make improvements. As a self-avowed sensor fan, watching how these little gems of engineering magic evolve is endlessly fascinating.