(My reply is specific to this happening in 2016. There will one day be Judge Dredd-like firearms. I don't see that being widespread in my lifetime, though.)

If you work in a company developing a hardware product you will learn, amongst other things, this:

1) The demonstration item is very likely hacked together at the last moment, and would 100% fail in the market if it was put into production at the time of the demo. (Even if your company does everything right, you are frequently only a part of the total product).

2) You never use the latest, shiniest, unproven technology. You use the simplest, production-friendly technology that will perform the job. Otherwise you are building a product higher than necessary failure rates.

(This is assuming that you aren't working for Google, Apple, Elon Musk or someone else who can put 100+ engineers on a sub-project and/or invent new meterials etc).

My assumptions are thus:

1) The manufacturers probably did the demonstrations to a) not be outdone by the competition and b) gauge demand.

2) No arms manufacturer has a robust, proven design that is affordable for civilian small arms. Going out on a limb I would also guess that none of them have either an experienced embedded engineering team or an intimate, effective working relationship with an external team. This is a significant expense (as opposed to a mockup for demonstration purposes), from which (3) follows:

3) The only way that a majority of customers will pay extra for this (anti-)feature is if legislation forces them to. California (and a few other states?) might try this, but given the NRA's lobbying power (and other factors) it won't be federal. If California tries it, it will be only for new firearms and perhaps even only for a certain group of sales/type of firearms, as a test. I don't see many such firearms being sold in the next 20 (at least) years.

Now, everything up to here has been some nice mental masturbation, rendered moot by the reality of a biometric-restricted firearm. These problems are non-exhaustive and can be solved, but it won't be cheap, easy or quick to market.

1) When the cheap "fingerprint" sensor with barely functioning, insecure firmware in your phone fails, no problem. If that happens on a firearm, big problem.

How can it fail? Battery runs out. Sensor gets smashed. Blood on your fingers. Finger cut/crushed AND blood on it. / Gelatine fingerprint. Real finger severed by criminals. Attacker owns a screwdriver.

2) RFID.

How can it fail? Battery runs out. Backup battery runs out. Tag gets smashed. RFID frequency gets jammed. / Tag gets recorded by someone walking past you. Tag gets recorded by someone with a directional antenna. When strong encryption is finally added, the implementation is flawed and gets cracked. One of numerous other RFID issues gets exploited (see Defcon, Chaos Communication Congress et al.). Attacker owns a screwdriver.

3) Dynamic Grip Recognition

How can it fail? Owner weakened by attack, fatigue or medical condition. Dominant hand damaged.

4) Conversion kits using any of the above

Since the aren't integral to the weapon, disabling or removing them will likely be very easy.

5) Source code of the firearm

You want to put a binary blob on my firearm? Firstly, no. Secondly I envision some interesting "unintended acceleration"-like lawsuits. (That reportedly cost Toyota about $1000 per line of source code)

Addressing all of these issues will take a long time and will be really expensive. And I'll bet the market will then end up with a DRM'd firearm that the owner won't really own. Maybe even connected to the internet, with a GPS and geographic fencing. There is a final addition which I would actually support: a screen and loudspeaker. Because then you can force the owner to view educational material on firearm safety, anger management, conflict resolution, the results of employing violence, responsible drug use and where they can find counselling w.r.t. all of the above.

Some things I would keep pushing for instead of an unreasonable electromechanical technological solution:

1) Firearm safety training in school / pre-school (ie. that it's not a toy, don't point it at people etc.). You should be training your kids regardless of your views on firearm ownership, you're not hiding the dangers of knives or cars from them, neither should you hide the dangers of firearms from them. The Brady terrorists will be against this, the practical result will be a contribution to continued accidental discharges by children.

2) Require all firearms, in all states, to be stored in a safe (which can't be opened (without a key!) by a three year old) when not in use. The NRA extremists need to stop politicking when it comes to requiring training and safe storage. Once again, a contribution to continued accidental discharges by children.

3) Instead of the planned invasion of Syria, put money into education in an intelligent way. Not into arguing about the math curriculum, but into social programs etc. to make finishing school and contributing to society more profitable (both in tangible and non-tangible ways) than doing drive-by shootings.

4) Decriminalize all drugs and let gangsters register their illegal firearms and join newly set-up shooting clubs with competitions and other places they can find stimulating jobs.

There, I've solved the USA. What's next?

PS. Something I think will (are?) sell(ling) are biometric trigger locks. People won't care that they don't work, since current trigger locks don't work either.