But if our dcs start in 2016, won't the fees for their courses stay at £9000?
No, I don't believe this is correct.
For those who started university prior to the 2012 increases to 9k, they indeed stayed on the previous fee regime (and loan arrangements) for their whole degree.
There is no such arrangement for those starting prior to the 2017 inflationary increases in fees, since the loan arrangements are not changing. If you read carefully what university websites are saying, they indicate that the 2017 fees will apply to all home students, not just those who start their courses in 2017. E.g. UCL:
""All fees quoted are for new students only in the session 2016-17 and relate to the whole session. Fees for subsequent years are subject to increase and this is implicit in accepting the offer of a place at UCL. UK/EU Undergraduate fees are capped by the Government and may still be liable to an annual increase."
For those who start in 2016 and end in 2019, the increase relative to the fixed 9k regime is likely to be 500 pounds, i.e. a very small fraction of the total cost.
For my own department, the increased fees in 2017 would result in an extra 100k of income for the department. This 100k would not even pay for a 1% increase in salary for all staff members, let alone cover 1% inflationary pay increases plus pay increases up the pay scale for early career staff (early career staff typically get 2% pay increases per year, i.e. 1% inflation plus 1% up pay scale).
I don't agree with student fees but it is not realistic to fix fees once and for all, and not allow them to increase with inflation. Nor it is realistic to fund universities at the rate Scotland is doing (many are close to collapse).