Leakage is the big problem in deep submicron. You can't keep a state without periodically refreshing it (cf. DRAM). Also, asynchronous circuits are very prone t

Leakage is the big problem in deep submicron. You can't keep a state without periodically refreshing it (cf. DRAM). Also, asynchronous circuits are very prone to metastability. If these problems were easily solved, we'd have seen this old idea be widespread by now.