Indentured servitude was tried in OTL. It didn't work, at least not on the right scale, because people from European climates who had to work outdoors on sugar plantations dropped dead of heat stroke at an alarming rate even by seventeenth-century standards. There might be ways to get more indentured labour in the northern parts of the OTL USA, but in the Caribbean and the southern states, slavery is much more likely to happen.
True, yes – but, let’s say that slavery is largely outlawed much earlier (say the various humanitarian leagues of the time were far more successful – or whatever makes you happy). Perhaps to off set the loss of a free work force and/or to make land holders happier about the whole idea the government introduces the gradual emancipation coupled with a more regulated indentured servitude practice.
(P.S. when I say government I usually mean the English Parliament – but in this case I meant governments in general)
What about everyone else. Any thoughts on what would bring this about or the effects it would have on history.