What amazes me about Cirulis is how the fuck he managed to nail it despite being an utter human shitstain. Talent and civility do not go together, it seems.
Care to elaborate?
Also, I think that while H1 story was great and unique, you can always invent the new theme that is great (or in other words - there is never a good time to call it "end of history"):
(i) standard - we came back but the evil is still there and retaliate
(ii) plot-twist - we really were "nazis" exiled and now need to cope with moral ambiguity "it-is-not-us-but-ancestors" vs taking moral responsibility
(iii) countless other fresh plots in-between...
It is really down to ingenuity of the writers rather than "the plot of the last game was so great it cannot be beaten EVER OMFG!!!" shitty explanation.