Mahesh,
There are various ways to counter 498a threat. One of the way is to file the DP3 case based on the statement given by her to the police in FIR. The judges also take this complain and many of them have successfully lodge the counter complain of DP3. I know one case where the judge said that the items mentioned are not of the dowry and so DP3 cannot be filed. He took that order and quashed the 498a case itself. So, just dont worry about the same, and you are right that the case can be filed, but one has to be persistant. If the police does not file the case, the court can admit the case u/s 156(3) of CrPC.