Chainring spacing has not really changed as the speeds have increased. Chains have gotten thinner and the ramps and pins on chainrings have become suitably more aggressive. That's not to say that no changes at all have been made but they were minor tweaks and AFAIK confined to certain 10 and 11 speed cranksets. Because the ramp/pin changes I would not recommend using a 7 speed chain on a 10 speed crankset. Chainring spacers are likely to create front shifting issues.