[Grammar] Is it natural to say "He will have been sick in bed for two weeks by tomorrow."?

[cabin]

Is it natural to say "He will have been sick in bed for two weeks by tomorrow."?

When someone was hospitalized 13days ago, is it natural to say "He will have been sick in bed for two weeks by tomorrow."?
My question is, if it is necessary to say "by" in this sentence, or not.
I thought the sentence with "by" sounds a little strange because he will have been sick for two weeks tomorrow and not anytime before tomorrow.
Well, I am not sure if I'm explaining clearly enough,,, but will you teach me which of the sentences below is correct or more natural or, both are OK:

-He will have been sick in bed for two weeks by tomorrow.
or
-He will have been sick in bed for two weeks tomorrow.

Thank you.

CABIN(Japanese)

 

[Raymott]

Re: Is it natural to say "He will have been sick in bed for two weeks by tomorrow."?

The sentence without 'by' is better.
I'd say, "It will be two weeks tomorrow that he's been sick [in bed]" or, to use your tense, "Tomorrow, he will have been sick for two weeks".
Of course, you're assuming he's not going to get better overnight.