Thank you for this article! I am a member of the Slimcoin community and I think you're totally right with the analysis that we need alternatives to Proof of Work.

The Slimcoin model uses three different block generation/consensus methods, being Proof of Burn the most unique one, but we also use Proof of Stake and Proof of Work.

This is not only better for security - pure Proof of Burn consensus could be relatively easily attacked in periods where few people participate in "burning" - but it has also the advantage that there is a better power balance. "Miners", "Stakers" and "Burners" are representing three different investor/business types and they complement each other, being burners the most long-term oriented group (and so they have a strong incentive to do everything they can to make the coin a success).

Some explanations are here: http://slimco.in/advantages/ , above all in the "Balanced power structure" section, and our Proof of Burn ELI5: http://slimco.in/proof-of-burn-eli5/ . Enjoy!