Could Go Either Way 〜かもしれない

かもしれない sits at the low end of a certainty scale that also includes だろう and でしょう, which you already know. だろう leans toward “probably,” かもしれない just says “possible, no more than that,” a genuinely open guess rather than an educated one.

Nouns and な-adjectives drop だ entirely before かもしれない: 家だ becomes 家かもしれません, never 家だかもしれません. Verbs and い-adjectives attach in their plain form with no change, and かもしれない itself never conjugates to match politeness, only しれません softens it for polite speech.