No deck is forever tiered. THis deck costs 60k that is impossible to get without money even for new player (there are onlu 100k gems in the game) and in time (you need 2 months to ammass 10k). As regard spore, there is no plant tuner deck, and even if there will be, it is not guaranteed it will be as strong as TCG back in the days.
I’ve had some success with synchro-sylvans using Spore. It’s easy to put spore into the grave alongside cards like rose lover or carrot warrior, making synchro really accessible when you want them
Obviously no deck will remain 'forever tiered', the statement is rhetorical; but as long as it's tiered during 1 YEAR, that's enough for me. I'm getting this deck.