VERY good AR coatings are already available- but the coatings with the least coefficient of reflection are designed for a very specific wavelength and angle of incidence.

If you take an un-coated glass lens and shine a visible light source through it, you can expect about an 8% loss of throughput- (About 4% per surface)- this doesnt seem like that much but if you have a system of 10 uncoated lenses/windows (20 uncoated surfaces) then the light at your output is ~%44 of what you put in (just counting reflection losses off your 10 transmissive optics, there will be other losses of course)... in astronomy every photon counts. An ideal optic would have a low coefficient of reflection that is the same for a wide range of wavelengths. With high power lasers a low coefficient of reflection isnt just nice, its a safety issue- a 4% reflection of a 1000 Watt laser is a fire hazard. A %.1 percent reflection is manageable.

Here is the reflectance versus wavelength curve of a high quality broad band (large wavelength range) AR coating from Melles-Griot:

While obviously better than an uncoated glass optic, it is hardly flat w.r.t. wavelength. Narrow band, (small wavelength range) coatings can get reflectances of a small fraction of a percent for a small range of wavelengths

It seems that the advantage of this coating under discussion is that it would seem to maybe have a fairly flat reflection coefficient W.R.T.wavelength... (barring the diffraction issue mentioned for shorter wavelengths, hard to tell from the linked article). This would be nice- less reflection means shorter exposure times, and a flat reflectance vs. wavelength curve means a little less work in analyzing data. Possible problems with the coating are:

1) How delicate is it? How often does an amatuer astronomer clean the optics of their telescope? Some coatings are very rugged, others can literally be blown off- where does this fall? If it is too delicate then your optic only lasts as long as it takes to become too dirty to be used effectively.

2) How sensitive is it to the environment? Would all those little fibers absorb atmospheric water easily and change their properties?

3) As pointed out, how expensive is it- (I would bet that its VERY costly now, and for the short term future) and since most amatuers use reflecting scopes with few transmissive elements how muce use would it be for the amatuer astronomer?

4) What surface area can be effectively coated?

This is an interesting technology, and it will certainly have uses, the question is how diverse will its possible applications be?