I do like to help with valuations when I can, but this is one I cannot say for certain.
Blended whiskies rarely increase in value in the same way as single malts.
If the presentation is the same as the current one of today, then it will have no greater value than the current 12 y/o bottling as there will be nothing to differentiate it from the current one.
Therefore, you need to ask yourself:
Is there any date on the bottle or packaging?
Is the bottle label, bottle shape or packaging any different from todays version?
If it is different, then it may have slightly more value than the current bottle.
Even better would be if it were a "Special Edition" for some event with the details included on the label / packaging.