The difference between instant access rates and term deposit rates is very small at the moment. There is little financial intensive to lock.
Will NAMA case a reduction in savings rates? Well, if NAMA passes, then their will be less pressure on banks to increase their deposit to loans ratio which might create some downward pressure on savings rates.
However, savings rates are been driven up at the moment by competitive pressures which are only increasing and the ECB is likely to increase rates late next year.
I would guess that term deposit rates will only be higher is 6 months time as speculation grows about possible ECB rate increases.