> "Ricardo's law of rent shows that indeed, even without artificial scarcities imposed by regulation, rent can go up forever as long as productivity is rising."
The rent-seeking that he established states that political regulation can artificially create a situation of scarcity thus resulting in high lands costs that benefit landowners.
Specifically, he illustrated this regarding the "Corn Laws" of Britain which were a politically induced import duty on grains of all sorts making the cost of bread more expensive for consumers. Famers could charge more for the grain they grew because of less competition but the landowners would simply charge the famers more money. Thus, the import duties raised the cost of food for consumers while indirectly directing that wealth to landowners.
The "Corn Laws" created the market inefficiency, market failure which interfered with wealth creation and David Ricardo even joined British Parliament to combat the "Corn Laws." He eventually succeeded in the repeal.
While the values might continue to increase with rising productivity, the overriding factor at least for today's environment is the "rent-seeking" and we need to reverse the local control of land which benefits wealthy landowners like President Trump over normal working people.
Rising prices are due to scarcity. The scarcity is politically induced in order to in this case benefit landowners. Reverse the scarcity, politically induced or otherwise, and prices fall.