I don't know what you're seeing in those stats. Bluesky has been shedding users since the inauguration. Mastodon is virtually a hobby project consisting of private servers that could run indefinitely as long as somebody finds it useful for communication in their community.

Neither have any shot of being a twitter replacement. Bluesky has a culture problem and a dishonesty about being p2p problem, and mastodon is too slow/heavy and has a mod problem that is intolerable without a better story about user mobility between servers.

Twitter may just die by itself if somehow a better way for people to publicize their work comes into existence, but all traditional means have been rolled up into big opinionated gatekeeping conglomerates who simply ignore things that compete with any of their interests or threaten any of their advertisers or owners. But even if twitter dies, people aren't moving to bluesky or mastodon.