A bunch of economically significant participants in the Bitcoin ecosystem have signed an agreement to ostensibly run code that would hard fork away from Bitcoin Core code later this fall. Why? And what will happen?

At the time of signing the agreement, the economically significant participants (some with hundreds of millions of USD on the line) must surely each have been aware that attempting to enforce a contentious hard fork would lead to severe risk of two chains, attacks, disruption, confusion, and lasting damage to Bitcoin's reputation, value and usage.

The participants must all now continue to be aware that attempting to ram through a contentious hard fork based on rushed code produced by a small handful of developers in a semi-closed process, with almost no time for testing and coordination with other ecosystem participants, will quite possibly result in a colossal clusterfuck.

Thus – provided that the participants have not been fully co-opted by forces hostile to Bitcoin's increased adoption, and provided that they are not otherwise no longer motivated by rational pursuit of their own economic self-interest – one would have to conclude that, regardless of their public statements or commitments, the participants will not be willing to actually move forward with such an unreasonably risky hard fork.

If so, as an uninformed outside observer, how then could one explain the fact of these economically significant participants in the Bitcoin ecosystem publicly pledging to honor an agreement that appears to commit them to a path heading directly into this unreasonable risk?

For a large fraction of the parties to the agreement, it seems reasonable to infer that signing the agreement simply represents pragmatic temporary signalling to move past a political deadlock, with the unspoken but clearly rational intent of shifting their stance on the timing and deployment of the 2x block size hard fork portion of the pledge, after Segwit activation, based on the obvious challenges a rushed non-unanimous hardfork would pose.

However, it also seems that some of the economically significant participants, in particular some of the miners, may have signed the agreement fully intending to run Segwit2x code, and may find it very difficult to explicitly back away from this pledge, either due to external pressures and/or being unwilling to lose face.

If those miners indeed earnestly follow through on their pledge, did the other agreement participants miscalculate? The prospect of substantial hashpower actually running Segwit2x code after Segwit activation would, at first glance, seem to imply the real chance of a contentious hard fork occurring this fall.

On further consideration, what seems most likely to happen is that the miners will indeed run Segwit2x code, and on the surface meet their publicly stated commitment, but those miners will simply set their soft limit such that they continue to mine segwit blocks that small enough to be valid according to Bitcoin Core code.

It would be easy to justify the soft limit as a temporary measure to allow time for "further testing" and adoption of "Segwit2x-compatible code" by more of the other nodes who variously were or were not party to the agreement.

After a couple years of further work and research, a hard fork to some form of larger block size might independently be developed, tested and accepted by Bitcoin core; in the meantime, soft limits would continue to be used as a means for miners actually continuing to run Segwit2x code to maintain compatibility with the vastly more prevalent majority of nodes continuing to run battle tested, well-maintained Bitcoin core code.

If this theory proves true, there may be many moments of fear and uncertainty between now and this fall, with plenty of posturing and sound and fury, and the Bitcoin price could dip substantially at points – but in reality those dips might be some of the last opportunities to add meaningful amounts of Bitcoin to one's holdings before the next phase of 2nd layer scaling solutions starts unfolding, and the value of Bitcoin takes off on another upleg, never to look back.