The antonyms for the phrase "becoming threadbare" could be "fresh," "new," and "vibrant." These words indicate a sense of brightness and liveliness, in contrast to the worn-out and tired appearance of something that is becoming threadbare. Other antonyms could be "sturdy," "durable," and "resilient," which suggest strength and the ability to withstand wear and tear. Additionally, "luxurious" and "opulent" could be antonyms for "threadbare," implying a sense of indulgence and extravagance. Ultimately, the specific antonyms for "becoming threadbare" will depend on the context in which the phrase is being used.