The age of peak democracy is already over. There was a period roughly from the American Revolution till the Spanish Civil War (i.e. 1776 to 1939) when popular revolts were a serious concern because the military technology favored strength in numbers even with amateur fighters. Since the 20th century, tanks and airplanes and rockets—expensive and specialist weaponry—allow even weak states to resist popular revolts (they can still suffer coups from low morale etc). Since the end of this period, democratic power has also declined, with legislatures subordinated to bureaucracies and where a global elite culture increasingly ignores the masses to institute unpopular policies. [Related (paywalled) reading from Ben Landau-Taylor.]

Europe is relatively less democratic (steamrolling the masses with unpopular policies like degrowth, mass immigration, etc. with less resistance than in America) while e.g. Latin America is more democratic, and America is in between. (In Latin America, elections are much more important because of their less complex bureaucracies, while I remember a funny German interview where a bureaucrat was asked for his thoughts on the upcoming election and he seemed not to understand the question, because of course he's certain to maintain his post regardless of the results.)

AGI is a centralizing technology but with respect to democratic power I predict that it wouldn't affect the trend because popular revolt is already an extremely limited concern, especially including factors not mentioned like the aging population.