Wouldn't number verification systems (for example, Facebook) eventually start blacklisting your numbers? I have seen this happen with VOIP numbers. Do you have a plan to tackle this?
From the perspective of a number verification system (or anything else sending an SMS to them), they are completely indistinguishable from a mobile phone and prepaid SIM, since that is what they are.
The virtual numbers, while also never re-used, are often blacklisted by services that do SMS verification due to coming from a range designated as "VoIP" or "virtual", and we explicitly disrecommend their use for verification, although some people do use them with varying amounts of success since they are cheaper than the SIM numbers.
This isn't true; UK mobile numbers are re-used after a period of inactivity by the operator themselves.
Unless, of course, you're keeping the number/line live in permanence? But I can't see how your service would make that work financially.
Of course unless phone numbers perpetually get longer, they have to eventually get re-used. We don't implement any re-use but the operator will indeed eventually recycle them.