This grammar pattern shows a speaker's supposition/conjecture about a future possibility.

- attaches to any verb except 이다
- the subject is usually in the 3rd person
- 리라고 생각하다 attaches to verbs ending in a vowel
- 으리라고 생각하다 attaches to verbs ending in a consonant
- (으)리라 by itself can be used to express conjecture or opinion about the future
— ex: 해외에서 일하면 외로우리라./If you work overseas, you are bound to be lonely (I expect/suppose/think that, etc. you will be lonely).

Examples:
제 아버지가 침실에 계시리라고 생각합니다./I think my father will be in his bedroom.
음악회에 가리라고 생학해./I think she will go to the concert.