Filecoin network storage limit due to deal expiry

In the [recent storage throughput calculator](https://beta.observablehq.com/d/37ff2d55942d1354) I put together, A previously un-worried-about factor popped up, deal expiry. Essentially, if we assume that there is some average length of time that deals are made for, even under a distribution with high variance, we set a 'maximum' throughput in the system.

Potential avenues of mitigation:
- Increase the block size
- Only gives us scaling linear to the increase in the block size. Not a workable solution
- Reduce the size of bids/deals
- A much better lever to pull than increasing block size, though getting smaller bids and deals is complicated. See [this doc](https://gist.github.com/whyrusleeping/b84aeb7c32a9d535ac51874dc7e14a42) on bid/deal aggregation.
- Increase the average deal duration
- Easier said than done, this means changing how people will want to use filecoin.

Start with the linked storage throughput calculator to reproduce how deal expiry limits throughput, then read the linked bid/deal aggregation document. Compare the proposed block-size, deal-size, and deal-duration avenues and determine whether the project has a chosen protocol change. The issue provides no implementation location, tests, or acceptance criteria, so a concrete definition of done is still needed.

Written by the indexing model from the issue text.