I will not discuss every aspect of the probable evolution of RFId tags, but to the new possibilities that you could imagine if you think in the combination of RFId tags and wireless sensor networks.
Active tags are currently used for more activities that just tracking. The are used as anti-counterfeiting and anti-tampering devices, in the food/health industries they are used to monitor the temperature of foods (like meat, milk) during the whole production-transportation-storage chain, they are used to monitor car tires pressure, and in a lot of different scenarios where in addition to tracking they are monitoring temperature, pressure, pH, light, etc.
Under these activities RFId tags could be considered wireless sensors, that in general transmit the measurements and information that are been monitored when they are in the proximity of a tag reader.
Wireless sensors in the other hand, usually are part of a network (wireless sensor network) that interconnect a group of wireless sensors in a mesh architecture to find a way to transmit data to the "outside world" by routing it through any other neighbor that could find a path to any point where the data could be recovered.
Under this idea you could think in RFId tags as part of a network of tags that could transmit information between them. In this scenario it is easily to assume that you will need less readers to retrieve tags data. For example you could check a whole warehouse of products jut by placing a reader near the closest one, this action could start a "chain" reaction of data transmission over the RFId network, and you could obtain the information without moving shelf-by-shelf.
Although this is just an scenario and lot has to be done to obtain this mix of tags and WSN in the future we will see several alternatives that will explore the mixing to some degree or another.
