You dont need some super strong military to supress rebellion and dissent. You can do that with intelligence gathering and surveillance, 24/7 media propaganda, cancel culture, a corrupt court system and aggressive targeted use of law enforcement, and those things are only going to be increasingly used to suppress dissent.

The US system wont collapse through open armed rebellion. It will do so through financial and economic mismanagement, corruption, crumbling infrastructure and societal dysfunction, open discrimination and oppression of your most productive members of society, and a lack of faith in the system. The Soviet Union collapsed without a shot being fired. A similar fate is increasingly likely in the US.