The device as it exits today is fantastic and it will play a giant portfolio of PC and emulated games until you wear out the battery and joysticks.
Go buy it on sale right now and enjoy it.
That doesen't make it tue. I worked in consumer electronics development in the past, and it was normal to deny any rumors of an updated and improved product being in the works because otherwise consumers would not buy your current stuff and just wait it out for the next better thing.
At release the Steam Deck competed with the Nintendo Switch, which doesn't run Steam. The Steam Deck has pushed Steam into the handheld market, but other devices can keep it going without a second Steam Deck.