i can't believe this still comes up and generates this much debate. it is really very simple.
it is myopia and focusing on short term profits vs long term growth, something that clearly has no place in freely interoperable systems, that drives this AMBE-encumbered dstar nonsense.
sure, making a new low bit rate codec is apparently not trivial, or ICOM et al would have just hired a few interns to do it rather than pay license fees.
also ignore commercial radio users because while they also lose out by having 4-5 standards, they have different interoperability and vendor support demands than amateurs.
there is a whole dustbin of history to collect technologies like AMBE: propietary and non - interoperable with others, implementation subject to secrecy or legal fees, usage subject to secrecy or legal fees, or requirement for centralized servers owned by one entity. these products can temporarily hold a niche that can eventually make them feel like a quasi-standard, e.g. AIM. ICQ. US Robotics HST vs v.std modems. US-CDMA cell vs [234]GSM. Eventually FaceTime, Hangouts, Skype etc will all fall here.
The only likely exceptions that occur are when duplication of the proprietary technology is easily possible and extremely unlikely to be prosecuted.
e.g. Microsoft windows and office found itself sneakernetted home from every office and school and organically become a de facto standard not by its openness or quality but by its cost to duplicate (~0) and ubiquity.
mp3 became a standard despite it being patent encumbered since it provided such overwhelming utility and ease of duplication -- just copy the binary that ran on everyone's linux box -- that usage took off while the license became slowly irrelevant (even if it still attracted trouble for entities with large attack surfaces for lawsuits)
hardware enjoys no such ease of duplication factor so AMBE chip codec isnt going anywhere for ~free, and since dstar offers no other voice mode (?) it cannot be worked around. even when reading the dstar wikipedia page red flags are raised when it starts mentioning closed binary daemons and the requirement to run ip accessible monitoring servers on gateways etc.
someone may eventually fit codec2 into dstar with dstar.proto.type==DSTAR_VOICE_RESERVED1 and it will technically work but only among tinkerers since the hardware won't understand those frames.
or maybe someone will eventually leak a test suite for AMBE from DVSI that includes a softmodem of the codec and it will be easier. but hams must ID unlike my earlier examples re ms and mp3 so rampant obvious use of the codec may attract legal attention. and again, no one is going to carry a laptop to run hacked AMBE as a HT.
this is not how you design an open system, and open systems are the ones that stick around in the long term. since dstar wishes to be a digital on the air network standard it might want to offer a few killer apps for free.
if i was wrong we wouldnt be reading this sub on (diverse server architecture), IP, TCP, http, https, html, browser, (diverse client OS), (diverse client hardware)
instead some closed network type like Banyan Vines would have won and be serving up the entire reddit experience for us to our PCs, or we would be reading this on AOL or CompuServe, or...etc.