usual pattern of decline
Big powers seem to die in same way over millennia. Growth, brief stability, arrogance breeding incompetence, decline, a brief recovery leading to political/military implosion. Something breaks their internal systems, long droughts, extended cold weather leading to famine and plagues,invasions. A few cases even economic collapse due to currency devaluing. One reason Dutch East India Company lasted so long was the backing bank maintained its currency value for a century. A century ago a pommie pound was good anywhere. Even cheques (Aus spelling) were regarded as solid.
As for wannabe subsequent powers, attempting to restore the "Gories of the Past" (sic) usually means a century or 3 of disaster.