Whoever becomes Pakistan’s next prime minister following Sunday’s dissolution of the national assembly faces a raft of challenges. The president dissolved the assembly just hours after the deputy speaker declined to accept a no-confidence motion that would likely have seen Prime Minister Imran Khan booted from office, meaning the country will go to the polls within 90 days. A poorly performing economy, rising militancy and shaky relations with former allies will be top of the agenda for the next administration, which will be formed after elections that must be held within three months. The inc…