This type of software is an excellent fit for "eventually open" licenses: https://news.ycombinator.com/item?id=12459492 This way, corporations and business users can pay to get the latest version and features just like commercial software, while the hobbyist community still gets a relative recent and feature-full release they can use for free, has source available and is guaranteed to become fully GPL code in 3-5 yea…
Another approach is to allow free non-commercial use, and to charge for commercial licenses. There are licenses that grant all the rights that non-commercial users want, but still require businesses to pay. https://polyformproject.org/licenses/noncommercial/1.0.0/ https://prosperitylicense.com/
What is needed is a non-repudiable commitment from the vendor that the software will be fully open source, and a business incentive for them to continue developing the commercial version; they have a few years to monetize any new features, and to continue making money they need to continue bugfixing and creating other desirable new features, as opposed to just milking the lock-in cow.