I wouldn't say "exactly same way" when it requires a massive redesign in both hardware and drivers, to both cache hierarchy and the scheduler - the latter of which AMD has had notorious problems with. Nvidia also estimates it would require a minimum of ~768GB/s per link to approach a monolithic die's performance and that's if you included the architecture changes to optimize for the MCM setup and if the workload is highly paralizable with minimal memory intensity - aka pretty much the opposite of games. So yeah, while MCM is definitely the future it's not as simple as "just split it and performance is within margin of error" it's going to take a lot of work to get it to similar performance as monolithic dies and it's going to be easy to run into software compatibility problems (mostly related to scheduling) that are difficult to solve - which again, does not seem to be AMD's forte. It's definitely possible they will go the route regardless.. like if you had asked me about HBM on consumer cards as early as 2015, in 2013, I'd say that was crazy, clearly AMD proved me wrong - but I just don't think it's the best decision for them short term. Nvidia doesn't seem to be doing it until 2020+ and I don't think AMD needs to beat them to the punch at it.