Verified answer

かわってくるだろう is not right. use 乾くだろう　（かわくだろう）

For native Japanewse, those sentences are the same meanings.

今5マイル走ると仮定したら、のどがすごく乾くだろう

Or

仮に今5マイル走ったらのどがすごく乾くだろう

So,,, in this case, "hypothetically if i ran 5 miles right now id get really thirsty"

もし今5マイル走ったら、喉がすごく乾くだろうね　sounds very natural Japanese for us. (you don't even need to translate "hypothetically" because "if" is the same meanings in Japanese, for this case )

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Your minor carelessmistake is only "っ" for ”い”.

The both will do as Japanese as they are.

今、5マイル走ると仮定したら、のどがすごくかわ"い"てくるだろう

仮に、今5マイル走ったとしたら、のどがすごくかわ"い"てくるだろう

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BTW:

What is difference between YOUR 渇いてくるだろう　and OTERS 乾くだろう.

First of all 乾くだろう　is wrongly written in kanji.

乾く is for; when you say "hang the laundry to "dry"".せんたくものを乾かします.

When you refer to "thirsty", 渇く is correct.

Thus, it should be 渇くだろう.

Now, I would say your かわいてくるだろう　（渇いてくるだろう） is very meaningful and sophisticated way to express such situations.

Why is that かわいてくるだろう implies a dry-mouth will develop bit by bit while you are running 5 miles.

You are awsome in sense of Japanese.

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