Just some spit-balling here, I'm sure I have some ordering and details wrong.
Mike and Gavin argue for no limits and ~free transactions forever, regardless of the costs.
Some in core suggest that if we really need to show the flexibility of a blocksize increase, 2MB could probably be sold and made safe enough (with planned future improvements) if we really had to.
Gavin gets some clue and realizes no limit at all makes no sense; Mike grudgingly agrees to go along with a 20MB proposal.
Miners reject that as unrealistically large.
Gavin and Mike retrench with a 8MB that rapidly ramps to gigabytes. Announce intent to adversarial fork the network in Bitcoin XT. A new client which is 99.99% code from Core but with the addition of the new expanded blocksize and Mike hearn declared benevolent dictator of the project.
In spite of announced intentions by some, almost no one adopts Bitcoin XT and XT development sits at a near standstill compared to Core.
Miners' notice the 8MB change isn't really 8MB and some aren't pleased.
Systems testing is finally performed on XT via testnet a month before it was intended to activate. Many performance problems are found with 8MB, person testing it suggests that 4MB or 3MB initially may be more realistic.
Core completes a years long development work which speeds signature validation >5x, invents a clean way to allow new efficiencies and security trade-offs, gets node pruning working, and comes up with a way to get roughly 2MB worth of capacity without a the risky and coordination problematic hardfork, while simultaneously fixing some long time bugs like malleability and misaligned incentives (utxo bloat).
Core posts a capacity roadmap including these solutions, along with a plan for further development to allow more capacity into the future.
Almost the entire development community and many in industry sign on an open letter in support of this plan. On the order of fifty people in all, it includes all of the most active contributors to Bitcoin Core and many other pieces of Bitcoin software.
Gavin, Jeff, and a few other people (including people involved with the recently insolvent Crypsy exchange) announce that they're creating "Bitcoin Classic"; a retry of the XT approach but with added popular voting on a centralized web voting site.
Mike Hearn catches fire, slams Bitcoin with a one-sided attack piece piece in the NYT calling Bitcoin a failure. Some argue that Mike's position is driven by his employment at R3, an adversarial to Bitcoin company working with major banks. Astute followers know this isn't true: Mike's misalignment with Bitcoin has existed forever.
Bitcoin market price crashes significantly.
Core creates a public test network for the new improvements and many people are actively testing on it. Several wallets begin their integration process for the new improvements. Development moves rapidly, several standards documents are written.
Market price substantially recovers.
Gavin finally announces code for the new "Classic", largely duplicating the XT functionality. Instead of the BIP101 rapid growth scheme, it features a 2MB hardfork, and none of the other improvements that are recently in core and in the works.
Bitcoin market price drops significantly again.
I'm hoping we get to the point where the market realizes it's being toyed with here and repeated XT reloaded attempts are pretty meaningless. We're not seemingly there yet.
Have I basically summarized the last year? Anyone want to add any bullets?
Great summary, very accurate.
For completeness, don't forget the first XT-induced price crash, and the wonderful #ScalingBitcoin workshops that Hearn declined to attend. Perhaps consider the role of the (shady cloud-mining) Toomir Bros and (shady Panopticoin pushers) The Blockchain Alliance, although they are really just footnotes.
3 cheers for BIP000; long live Bitcoin Core!