Avangi, I know you said you would rewrite if clause in present tense. However, I'd like to understand why you wrote it in the present tense followed by woulds. I'm sure your structure is correct and natural and by understanding it, it'll help me understand native speakers better and follow native speakers' conversations better.
Believe it or not, I've tried to understand this type of structure many times but am still lost.
Please help thanks!
If you just say, "I'm gonna be late," you probably would(3) have already tipped the person off that you would(4) need to end the conversation soon, and as you suggest, you would(5) still expect to be on time if you left immediately.