Yes on a temporary basis , Wales vs Australia the following week will then have a bearing on the outcome.
Any of those 5 teams could be ranked above Ireland at the end of November tour: Argentina, Scotland, Wales, Italy , Samoa.
The best Ireland can hope is 6th, the worst would be 11th if Wales, Samoa , Scotland and Italy all win and Ireland loses.
Anyway, Ireland controls its own feat, a win will secure the second seed regardless of any other results as it guarantees being ranked above Italy, Scotland and Argentina.
The top of four are almost secured, it would require some huge upsets for England or Wales to catch up with either Australia, South Africa or France (Wales would need to beat the ABs and the OZ with other results going their way). Only the ABs are numerically guaranteed to be in the top 4.
The IRB rankings are normally quite boring except now as the current games may have a huge bearing on the outcome of RWC2015.