On the basis of the Hadith that says that whoever dies without knowing the Imam of his time dies the death of ignorance, does that mean that Sunnis, therefore, will be unable to enter paradise?
It is not our job to determine who will enter Paradise or who will not. Allah knows the intentions and circumstances of every creature, and He grants Paradise to whom He wants, according to His Knowledge and Mercy.
No doubt, the authentic Hadeeth is mentioned in both Sunni books and Shia books states that: Who dies with out giving allegiance to the Imam of his time will die a death of Jahilyyah. ( Musnad Ahmad bin Hanbal, v,13, p. 188 and Saheeh Muslim, v.6, p.22 and Kitab Al-Sunnah by ibn Abi Aasim;489 and many other books of Hadeeth.
Wassalam.