Exactly how removing an AU account will affect you depends on your credit report.
Imagine looking at your CR with the AUI accounts gone.
If the AU account is old it will lower your average age = -FICO.
If the AU account has good util % removing it will raise your overall util% = - FICO.
If the AU account has good paymanet history then you will lose that history = -FICO
If the AU has 0 balance removing it will alter the number of 0 balance % = -FICO
If the AU is at high util% removing it will lower overal util = +FICO
If the AU is newer account removing it will increase average age = +FICO
If the AU has derog removing it will remove them = +FICO
If the AU has no zero balance removing it may alter % of 0 balance cards = +FICO
So it really depends. However removing an AU for the sole purpose that FICO 08 might me used in future is not a good idea.
1) Nobody knows for sure when it will be used.
2) When FICO-08 is implemented AU are simply ignored they don't have a negative impact. It is like the AU are completely removed (all + or - effects above) when calculating your FICO. Any + or - will be the same as if you removed them.
So if FICO-08 is going to result in a lower score than removing the account now will just give you a lower score sooner.