Yonai, Tojo, and the decision to end the war

Would Hideki Tojo still become prime minister during this war?

Possibly, but Mitsumasa Yonai could instead take office and seek peace; an army takeover might remove Yonai and prolong resistance despite Japan's worsening strategic position.

The blockade does not determine surrender by itself because Japanese political leadership still has to interpret the military crisis. Navy Minister Mitsumasa Yonai understands the danger of war with the Western powers and might negotiate. A Tojo or army-dominated government could reject that course and marginalize or kill opponents such as Yonai and Yamamoto. The same naval defeat and economic pressure can therefore produce different war-termination timelines.