It's a lot more practical to put several dies insides one package, which is already happening (for example, the largest FPGAs from Xilinx have 4 dies in a single package).
Intra-package communication is not quite as good as intra-die communication (from a performance and energy point of view), but it's a lot better than inter-package communication, and several small dies have a higher yield than one large die.
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