"Once the format is finalized, the next logical step would be to make a library version of it, which will be most probably get licensed under the LGPL v3+"
LGPL is only marginally better (at least as it concerns perceptions, if not reality), especially when you factor in app platforms where shared libraries aren't commonly used.
Basically anything copyleft is going to have a really big dropoff in use compared to say BSD, MIT or Apache 2.0.
Except that game developers are already using LGPLv3, especially on the PC market which is only worth $25 billion in size.
A key attribute for companies in a heavy competitive market is that they have to use every tool available to get the best product out in least amount of development time. If a company decided to avoid a license just because of religious reasons, 10 other companies will jump into its place and out compete them.
A good example of this is when we see companies reaches out to developers directly to get permission, as the time to do that is worth compared to having developers spend time on unnecessary code. Large AAA games can easily have a long credit list of every license available that can be used in a proprietary product, including LGPLv3.
There are always exceptions, we are talking about the general case. Anecdotally, in my professional experience every commercial developer I've worked with or am aware of will always avoid any copyleft-licensed material and many license agreements for third-party platforms prphibit their use.
Yes, some platform holders will use it themselves, but that is not their preference. Ultimately, image encoding and decoding is a crowded market with many alternatives and I strongly believe that a copyleft-licensed component will always be passed over in favor of alternatives unless it is overwheingly compelling and a viable option.
Some companies explicitly prphibit the use of any copyleft licensed software in their development.
Certain conditions of the GPL and LGPL are impossible to fulfill on some platforms.
With that in mind, I feel like my assertions remain reasonable.
"Once the format is finalized, the next logical step would be to make a library version of it, which will be most probably get licensed under the LGPL v3+"