Later Raghunathrao aligned with the British and this eventually led to the 1st Anglo Maratha War.
Other external challenges included the Nizam and Hyder/Tipu.
Nana was an excellent statesman, and a strategist. He had the foresight to identity future challenges.
'With him departed all the wisdom and moderation of this (Maratha) court.'
Just two years later in 1802, internal rivalries resurfaced, and British got an opening...resulting in the 2nd Anglo Maratha War.