A very interesting article on Mobile Business Briefing yesterday quoting Harbir Sing Nat, CEO of Zapp, a portuguese CDMA-450 operator. There's a bit of ranting about: how MNOs can expect low ARPU from utility meters (no big surprise there), how no-one's likely to want to support M2M customers on 700MHz LTE networks (again, not a shocker) and that shutting off 900MHz will leave big gaps in GPRS coverage (it won't for the many operators that only have 1800MHz spectrum and we can't see all MNOs in a given market switching off GSM for the foreseeable future). So nothing earthshattering there.
But, after that he does mention something pretty sensible: M2M and 450MHz were made for each other. 450 has good coverage, particularly CDMA, making network economics better. At a low frequency it should have better indoor coverage than other frequencies. It's largely unused spectrum that has become commercially redundant. There are some disadvantages, notably support for the frequency amongst module manufacturers. Also, there's no consistency internationally, so no good for any M2M application that requires roaming.
Overall I think it's a bit of a bonkers idea since the economics of running a 450MHz network just to support M2M almost certainly don't add up. But, there may just be a kernel of an idea in there for anyone with 450MHz spectrum.