It's difficult to guess what will happen -subject complement

[passengerman]

Hi all;

"It's difficult to guess what will happen"

What's the subject complement of the sentence?

"difficult to guess" or "difficult to guess what will happen"

 

[entangledbank]

In this case it's just 'difficult'. The infinitive clause is the extraposed subject. It could also be made the actual subject, instead of dummy 'it':

To guess what will happen is difficult.

Note that this has a dummy 'it', but with a referential 'it' (one that actually means a thing), the analysis would be different, and 'difficult to guess' would be the subject complement:

The answer to the riddle is difficult to guess.
It's difficult to guess.

 

[passengerman]

Many thanks entangledbank, I got now