That's non of the concern of the unlicensed spectrum.The LTE-LAA guys should do their work and come prepared for what is common in the unlicensed world. Not the other way around.
And open competitiveness is key in the unlicensed band.
BTW, there are precedents. In the IoT/M2M space Sigfox uses an unlicensed band around 900 MHz (from memory), and you can't buy their base stations: they make them for their own use, as their business is to be an operator. If you want to compete with them, you need to develop your own equipment based on a different scheme. WiFi and BT are the best known techs working in unlicensed bands, but there are proprietary systems too.
The legal constraints on the unlicensed bands are varying depending on country. But as far as I know the strictest constraints are:
- limited transmission power (LTE-LAA won't be allowed to shout above others at 5 GHz, at least where this constraint exists);
- requirements to do listen-before-talk (LBT), at least in Europe (but not in the US);
- limit on the amount of consecutive time a given device can hold the medium (5 ms max.).
LTE-LAA (not LTE-U) will be able to comply with all of this. In this sense, strictly limited to legal constraints, it will behave as is common in the 5 GHz band. To put more restrictions would need to happen at a legal level. And not surprisingly, there's intense lobbying on this topic happening right now from all parties (Google paper is part of this). To be followed...