Seeing the trends to commodify social rights, what steps can be taken, from a legal, social, academic, political point of view to make the transition from a "liberal democracy" to a "social democracy"?
Well, this does happen quite regularly in western liberal-democracies. In liberal societies there is a key problem: the tend to insist upon the sanctity of private property rights, so no social-democracy here (now usually called libertarianism), but graft on democracy and social-democracy possible if people vote for it. It can also slip back if voters change their minds.
UK, for example, free-market liberalism until 1911. The rudimentary state welfarism. 1945 onwards social-democracy. Reversed under Thatcher. Destroyed by New Labour. Back to rudimentary welfarism bordering on libertarianism. See my paper "Lest we forget: the case against charity at the end of the nineteenth century."
Liberal democracy is a liberal political ideology and a form of government in which representative democracy operates under the principles of classical liberalism. it is characterised by elections between multiple distinct political parties, a separation of powers into different branches of government, the rule of law in everyday life as part of an open society. On the other hand, Social democracy is a political, social, and economic ideology that supports economic and social interventions to promote social justice within the framework of a liberal democratic polity and capitalist economy. We can achieve the social democracy by enriching the values in liberal democracy.
Following link may be more useful for subject insights.
I have a friend with a Ph.D. in Public Policy who seems to have beliefs that resonate with the conclusions of Alexis de Tocqueville. My friend believes that humanity is cursed with self-interest and therefore any democracy will ultimately fail as people vote their self-interest to the detriment of the whole. America may provide an interesting test that theory in the coming decades.
Liberal Democracy died out some decades ago when the voters learned that their high taxes were going mainly to support middle class government employees. The Regan Revolution and Thatcher Revolution replaced Liberal Democracy.
Social Democracy was popular when I lived in Europe. It has fallen out of favor with productive working people, but remains a favorite among the unproductive faction. while it still continues in abbreviated form just as Liberal Democracy has it's supporters and pretenders.
For the question there is no clear way to convert from one to the other, and no obvious reason to do so. These ideas and supporters had their chances 40 years ago and failed to deliver a society acceptable to a majority of voters. Opinions of moderate voters are the governing forces, although many self appointed radical leaders try to impose some other direction.
A peaceful reform to an earth sharing economy is possible:
Research ECO-LOGIC DEMOCRACY -The Geonomic Argument-
The current rise of right-wing authoritarianism, the fusion of the state and the economy by maintaining the rentier capitalist business order, confirms the observations of Prof. Leonid Grinin: https://www.socionauki.ru/journal/articles/129622/
The societal future needs economic democracy, which is geonomics:
Dear Dr. Ternyik: I am confused. Are you suggesting that “right-wing authoritarianism and the fusion of the state and economy which maintains the rentier capitalistic business order” should be replaced by left-wing authoritarianism that destroys the historic social and economic contributions of non-governmental enterprises constrained by willing exchanges between buyers sellers, price consciousness dictated by supply and demand, and governmental redistributions and regulations when deemed necessary? In my mind and experience, “the state” does not create economic value, it merely collects and redistributes the economic value created by others – namely “non-governmental enterprises.” Help me here. I understand the “social” base, but what is the “economic” base of “economic democracy?” Please tell me “economic democracy” does not mean that “people with no skin in the game” get to vote on who benefits from the hard work expended and risks taken by those creating “true economic value” in non-governmental entities. Thanks in advance for any light you can share.