And yes, I did say "when" not "if". Spartan II's remain the most impressive and powerful of the generations, so I would think the Spartan V program would seek to replicate that again. Maybe even going back to using children again but with a twist of some sort, such as the children being volunteered by their parents, or the kids being exact clones of the Spartan II's themselves.
Well that would be an interesting prospect. However, we have to take some things into account:
After finding out about the abducted kids, the UNSC isn't in the highest opinion at the moment. The UNSC has pretty much never been in high regard with all of humanity, come to think of it... So I don't think paren't would willingly give their kids to ONI for experimentation.
The other part of the premise also needs to be discussed: cloning. This is feasible... partly... as it is how AIs, at least 3rd generation AIs, are made. They flash clone a deceased brain. ONI has flash cloned the Spartan II candidates in the past already, when they abducted them in the first place... but they all died of complications because flash cloning a full human doesn't work. Individual organs, they are fine, but a full human hasn't succeeded yet. We need some lore in the advancement of the technology first before this is a possibility.
However, with the advancement of robotics, I wouldn't be surprised if they used AI from previous spartan brains... oh wait, Halo 5 exists. Thanks Brian Reed. X (