Learn Hardcore Japanese: housouzikan ha henkou ni naru kamo siremasen.

は marks the topic, the thing you’re talking about. Here, it sets up “broadcast time” as the topic.
The grammatical subject of なる is implicit (think “it”), but with topics you don’t need to state a subject.
Using が instead would make 放送時間 the grammatical subject and feel more like introducing new information or answering “What will change?”
Nuance:
- 放送時間は変更になる… = As for the broadcast time, it will be changed…
- 放送時間が変更になる… = It is the broadcast time that will be changed…

Why is it 変更になる and not 変更する?

変更 is a noun (“change/alteration”). Noun + に + なる means “to become (a state),” so 変更になる = “to become a change” → “to be changed.”
変更する is transitive (“to change [something]”). You’d use it when an agent is expressed: 放送時間を変更します (“We will change the broadcast time”).
In notices, Japanese prefers agentless, neutral phrasing, so 変更になる is common.

What does the particle に mark in 変更になる?

に marks the resulting state with なる. It’s not an indirect object here. Think “become into X.” So “become into a change” → “end up changed.”

Could I say 放送時間が変わる instead of 変更になる?

Yes. 放送時間が変わるかもしれません is natural and a bit less formal. Differences:

変わる = “to change” (native verb, general).
変更になる = “to be changed” (Sino-Japanese noun + になる), sounds more businesslike/announcement-like.

Why is it なるかもしれません and not なりますかもしれません?

かもしれません attaches to the plain (dictionary) form of the preceding clause. You cannot put ます right before かもしれません. So:

Correct: 変更になるかもしれません
Incorrect: 変更になりますかもしれません

What exactly does かも(しれません) mean here? How strong is it?

It expresses possibility (“might/may”). It’s weaker than でしょう/だろう (“probably”) and often softer/more cautious than と思います used for guesses.

What’s the difference between かもしれません, かもしれない, and かも?

かもしれません: polite.
かもしれない: plain/casual.
かも: clipped, very casual speech. Example: 放送時間、変更になるかも。

Is かも知れません with the kanji for “know” okay? Why しれません?

Both かも知れません and かもしれません are acceptable. Modern writing often prefers all-kana. It comes from 知れる (“can be known”) → “cannot be known for sure,” used idiomatically as “might.”

Can I combine かもしれません with adverbs like たぶん or もしかしたら?

もしかしたら/もしかすると + かもしれません is fine (adds emphasis): もしかしたら変更になるかもしれません。
たぶん (“probably”) + かもしれません is usually redundant or sounds odd because their strengths overlap. Use one or the other.

How do I say “might not change”?

Negate the verb before かもしれません:

放送時間は変更にならないかもしれません。
Or with 変わる: 放送時間は変わらないかもしれません。

Is 放送の時間 okay instead of 放送時間?

Grammatically yes, but 放送時間 (a set compound) is more concise and standard in schedules/announcements. 放送の時間 sounds more descriptive or casual.

Can I drop parts in casual speech?

Yes, often:

放送時間、変更になるかも。
放送時間、変わるかも。 You can drop は and even 放送時間 if context is clear. Don’t drop に after 変更; 変更なる is ungrammatical.

Is 放送時間は変更されるかもしれません okay?

Yes. That’s a passive form (“may be changed”), a bit more direct and can subtly imply an agent. 変更になる is more neutral/polite in announcements.

What about となる instead of になる?

となる is a more formal/literary variant and is very common in notices: 放送時間は変更となるかもしれません. Both are fine; となる sounds slightly stiffer.

Are there other common announcement-style alternatives?

Yes:

放送時間は変更になる場合があります。 (“There are cases where…”)
放送時間が変更となる可能性があります。 (“There is a possibility that…”) These sound standard in disclaimers.

How do you read the words?

放送時間: ほうそうじかん
変更: へんこう
かも（しれません）: かも（しれません） Full reading: ほうそうじかんはへんこうになるかもしれません。