I think the safest way to go is to purchase products with open standards, namely Z-Wave and Zigbee. They're open protocols that can be used with any number of HA products; SmartThings, Wink, Vera, etc.
You can purchase Z-Wave thermostats from Honeywell, switches from Leviton, locks from Schlage and so on. I use OpenHAB in my home, which is an open-source home automation server. It can run on anything from a RPi to a blade with just a few necessary additions (namely a Z-Wave dongle and some sort of network connection.)
OpenHAB requires a fair bit of programming knowledge and the learning curve can be steep for some, but overall it's very functional. A few things I do in my house:
- When the garage door opens and it's after sunset, the hallway lights turn on and set themselves to 50% brightness.
- When I start watching a show on PleX, the living room lights fade out. If the show is paused, they'll come up enough for me to navigate around and refill my drink.
- When both my girlfriend and I are gone from the house, the A/C shuts off. When it detects we're within 1/2 mile of the house, it'll come back on so it's comfortable when we arrive.
There's a million other things you can do with OpenHAB. It has hundreds of "bindings" to different HA products and supports HTTP endpoints, etc. Proprietary standards are bound to go away eventually, but open standards with open-source software will always be around.