There are some equivalents already in existence (spin qubits in CMOS processes), that use the exact same lithography techniques. There are a few other potential

There are some equivalents already in existence (spin qubits in CMOS processes), that use the exact same lithography techniques. There are a few other potential alternatives too. All of them suffer from harder engineering challenges than the much "easier" to produce (in small volumes) transmons and trapped ions/atoms/molecules. Thus a plausible future is one in which the first somewhat-useful quantum computers are tens of thousands of qubits in transmon/ion hybrid systems. Then (in that plausible future) the spin qubits in CMOS do catch up, and thanks to their superior manufacturing scalability, they blow past the capabilities of transmons/ions. Not too different from how we had to use vacuum lamps while we figure out how solid state systems can work... Or spinning hard drives before we figured out SDDs. Or maybe none of this would work out and the whole field would be a bust... but you know Clarke's laws https://en.wikipedia.org/wiki/Clarke%27s_three_laws https://en.wikipedia.org/wiki/Clarke%27s_three_laws