As in Jude one:seven we see that eternal means simply until God's will is done, but I believe the eternal punishment of sinners is death,
Eternal punishment as in 'second death' which is: destruction. [Gehenna]
Jude verse7 refers to Luke [17v29] where the wicked were: destroyed.
Even Satan will be destroyed in 'second death'. -Rev 21v8; Heb 2v14 B.
Whereas the majority of sinners [Romans 3v23;5vs12-19] will be resurrected. [Acts 24v15]. Resurrected to either life in heaven [Rev 20v6; 14v4; 5vs9,10], or an earthly resurrection during Jesus messianic earth-wide reign of one-thousand years over a paradisaic earth.
-Psalm 72v8