its really hard to say how they will do it this year. From what i hear, last year they scaled 4U pretty high, which is which there has been alot of people doin 4U this year (at least in my school), which might mean they will reduce scaling to not as high as last year. But there is also other people who say that your 4U mark really depends on your 3U mark, so the main thing is to go really good in 3U and go ok in 4U and you should be scaled really well.
but again, others still reckon, and this is what i think, no matter what happens in terms of scaling, 4U is still goin to be one of the, if not the highest, scaling subjects, so you shouldnt really be worried.