It’s not inevitable – the sticker packs (as currently implemented) live on your homeserver. So in a sense, it is decentralized already, and it’s only a matter of designing and building an interface to manage those packs (and hopefully making stickers link back to the packs, for better discoverability).

For now, you can override which server to use for the stickers. There’s an implementation that downloads Telegram sticker packs (but you have to specify which packs you want before deploying it).