Some variation of this rumor has floated around for years now. Every year we get people saying Apple’s going to change the band design and make old bands incompatible with new watches.
Will it happen at some point? Sure. Do I think it’ll be this next year? No. A magnetic connection seems like the exact kind of thing Apple would want to do if it were practical, but for a device that is used in the range of activities the watch is, it’s not.
Imagine if the same complaints were leveled at people every time Samsung put out a new watch, phone, or tablet. Some of these are just cell radio variations, but come on.