Well, Core must be motivated to deossify somehow, and implement the features and respect the design decisions that were outlined by Satoshi.

I believe that the solution that fiatjaf and others seem to support (and myself as well) is drivechains, which will be demonstrated in the upcoming ecash fork. I am not absolutely sure that drivechains are the solution, many people have outlined concerns with the need for miners to participate in governance, but I am relatively sold. Regardless, Bitcoin has benefitted immensely from past controversial forks (it might not exist at all if Bitcoin Cash hadn’t found and magnanimously helped fix the inflation bug for everyone) and we should encourage any honest and decent man of good character that earnestly wants to fork Bitcoin to demonstrate new ideas and continue to improve the software in parallel to core.

You can also help by simply refusing to use anything that introduces centralization in cryptocurrency and warning others of the problems. This includes, to my eyes, LN, but others have disputed that point given that you can, in theory, have decentralized, noncustodial LN, but in practice less than 1% of people ever will do so due to the inherent qualities of the protocol.