i'm not sure in a world where you want to get rid of pow (cause climate narrative override everything), you will define blockchains as securities or not because they started pow or not. Also, that definition and its implications is different for each country. Eth was premine, it had issuers. Imho, you have tons of better ways to define security, like utility. In this space we have hundreds of companies selling a token and promissing huge return on investment, it wouldn't be hard to qualify those tokens as securities without having to bother with pow / pos