Mission:Impossible

Short Answer: Geological threat

The Mission: Impossible film series has already had six films in 20-or-so years (from 1996-2018)-- not bad at all for a franchise based on a TV show from the 1960s, one that had to complete with many other spy franchises from James Bond on down.

M:I is now coming up with a grand finale so grand it needs two parts, functionally Parts 7 and 8 of the series. Which is also going to be a send off for Ethan Hunt. (Tom Cruise is 60 years old this year.) 

But the threats Hunt has faced down have largely been... similar: plagues, nukes, conspiracies.

What about, though, a more sci-fi threat? Tesla (the actual person, not the company) created an earthquake machine. Once he created it and got it to work, though, he destroyed it. But what if someone found the plans? And scaled it way up?

Or what if the bad guys threaten the global water supply? Threatening water access was used for one of the Craig-era Bond movies, but only one country's water was attacked. Hoarding water is also part of the plot of Chinatown, but again, only for one city.

Pandemics are clearly a threat to global stability, but an earthquake machine threatens global stability much more literally. And actual companies are taking the nation's water and selling it back to us, one plastic bottle-full at a time.

Meanwhile... nukes? In the 21st century? Maybe back when the M:I TV show was on... And the evil-conspiracy angle-- while still used in the Marvel movies (Hydra, etc.) is also as old as Bond's foe Spectre.

Another possibility is to borrow plot from Shakespeare. Specifically, A Midsummer Night's Dream. The play's plot is full of masks, mind-altering drugs, mischief-makers, and double-crosses. It would be interesting to see the plot played out in the realm of spies.