Can Diffie-Hellman be scaled up or force-multiplied?
Short Answer: Yes

Long Answer:
From what I understand about quantum computing, they are only more efficient as long as the bit-depth of the problem falls within the bit-processing capabilities of the quantum processor. Example: a 64-bit quantum processor could solve 64-bit traditional encryption keys in a near-zero real time. 128-bit keys would still take a very long time, as would 256-bit. 512-bit, 1024-bit and higher bit-depth encryption schemes. Even if quantum computers get much much much more powerful, it is fairly easy to scale the key size to an arbitrarily high number of bits to defeat quantum computing methods.

Diffie-Hellman keys can be generated for very-high bit lengths, as it is not difficult to generate the numbers required for it. It IS, however, difficult so solve, and that hasn't changed, and likely won't change for a very long while.