What is the grammar structure for 살고 있을까?
For the sentence:
그 집에서 누가 살고 있을까?
Do you think someone might be living in that House?
This example is from Billy Go Korean's show: https://youtu.be/v7b3zoSYBjU?t=4m13s

I don't understand how 살고 was transformed to become 살고 있을까?
TTMIK suggests that might should be translated as: (으)ㄹ 수도 있다. http://talktomeinkorean.com/lessons/level-3-lesson-22/
I found that 을까 https://www.howtostudykorean.com/unit-3-intermediate-korean-grammar/unit-3-lessons-59-66/lesson-63/ is used to ask a question, but I still don't understand how 살다 became 살고.

Question

What is the grammar structure for  살고 있을까?
For the sentence:
그 집에서 누가 살고 있을까?
Do you think someone might be living in that House?
This example is from Billy Go Korean's show: https://youtu.be/v7b3zoSYBjU?t=4m13s

I don't understand how 살고 was transformed to become 살고 있을까?
TTMIK suggests that might should be translated as: (으)ㄹ 수도 있다. http://talktomeinkorean.com/lessons/level-3-lesson-22/
I found that 을까 https://www.howtostudykorean.com/unit-3-intermediate-korean-grammar/unit-3-lessons-59-66/lesson-63/ is used to ask a question, but I still don't understand how  살다 became 살고.

Answer

This is the ~고 있다 construction.
Think of it as "ing" in English.
Live ---> Living