The Atlantic had a little blurb this last weekend about a historical what if. The what if involved the American Revolution, and they brought in Harry Turtledove to talk about what if the American Revolution had failed. It was a nice way for him to pimp his book, The Two Georges (and another crappy book), and speak in happy tones about the positives. His book, co-authored by Richard Dreyfuss, is quirky with an alternate timeline director of the North American Union of Martin Luther King. I will stop as it is popcorn film quality in paperback form. For a media entity so in touch with diversity, it is interesting that The Atlantic did not ponder the diversity of the colonies around 1776. What could have happened had the revolution failed and simply been a rebellion?
Let us leave out foreign consequences (French Revolution, Australia/New Zealand development, etc.) with one exception. The Louisiana Purchase would still have happened because while not as horribly in debt, the Bourbons would still have needed to raise cash to pay off their considerable debts to stave off the Revolution. Do readers honestly think the British would have treated every colony the same? Are modern people that ignorant of American history? I shouldn't ask that. Yes they are. We are 10 years from American children thinking Louie Armstrong was the first man on the moon, inspiring him to write "What a Wonderful World".
First and foremost, leading lights of the rebellion would have been hung from trees as a warning. Enough would have been killed to cower the others in fear. A redistribution of the land of leading rebels would have created a nice, new client class of leaders for the monarchy to use for local support in the colonial administration. It was a favorite of monarchs in feudal times: kill off or ruin 'other' elites and replace them with your hand picked elites. Tories and loyalists of all stripes would have enacted revenge on those patriots suddenly in the lurch who had been suppressing and harassing them in the run up and during the revolution. The merchant class that leaned loyalist would have stuck around, possibly leading to actual class split along the British system of high-middle-low.
To wonder if the US would have been like Canada is an insult to the colonies. They were not one unit. That would not be settled until the Civil War. The British handled different parts of the Empire in different ways, and the Atlantic coast would have been a hodgepodge of administration. The southern colonies had far more loyalists, the Cavalier effect, and would have been treated better than the north. The mid-Atlantic would have seen an elite house cleaning. New England probably would have been handled like another hot spot in the Empire: Ireland. Massachusetts would have been on lock down. If anything, Massachusetts would have served as a warning to the other colonies.
Development would be slightly different because without Alexander Hamilton there to reorganize finances and suppport stealing manufacturing technology, the US may have remained a commodities powerhouse for decades (think pre-1912 Argentina). Manifest Destiny still happens, Indians still die, the Brits do not stop immigration, and slavery ends with a massive buyout. Abolition itself may have progressed slower since the war and later competition with southern commodity input pricing helped push British policymakers down the abolition path.
Would refional identities harden if provinces developed out of the colonies? Most likely. Those identities are alive today. It would have also benefited the crown. No American colossus would rise. Eventually provinces would declare independence, but their money would display British monarchs. Without a doubt, the Crown would play regions off one another to ensure another rebellion never happened.