You've committed a few small sins with this question. First you asked a question about a highly complex subject with a minimum of effort on your part to make the question easily answered. Second, you used an acronym that many people will not be familiar with. Third, there are a variety of devices that are used to ensure optimal grid performance. FACTS is not really a problem, it is a class of devices designed to enhance grid performance!
In the past, many times these grid performance problems were dealt with after they became apparent. Remember that loss of grid capacity or excessive loss of power ends up costing $$ and that many of the factors that contribute to these problems vary day to day. Predicting these problems is as much a statistical problem as electrical. Let us take an example of a new industrial area being planned. We know the industrial area will cause a lot of inductive reactance. So first thing the planners would want is to have a is new substation to provide power to the industrial area to allow that reactance to be controlled there and not affect the existing grid.
Ok, we now have more options than in the past, more devices and better modeling. In some of the new smart grid models there are automated measuring devices and automated correction devices. I believe you will see a proliferation of the measuring devices and the correction device then only employed where required. Since the correction devices are now available in a wide variety of types and sizes you will eventually see these down to the individual customer level. Then one customer that uses a lot of high powered motors will not effect the power factor of his neighbors.
This is also a boon to distributed generation in that if a solar/wind generator is installed in a grid area that has imbalances a DVAR may be used to inject power with a counter balancing power factor, and by doing so, stabilize the grid.
Here's a link to a paper with the stated goal of maximizing the loadability of the grid:
http://www.ijsei.com/papers/ijsei-10312-04.pdf
