I think you have to be a little pragmatic the link between inactive and shunning.
As has been pointed out "inactive" is a procedural term related to field service. If you don't turn in a report for 6 consecutive months you are inactive. In itself, it has nothing to do with meeting attendance. You can never go to a meeting but be active just by turning in a report each month.
As has also been pointed out, if this is also linked to not being present at the meetings and other aspects of Witness life then the longer this carries on then the less notice the elders will take. That is not to say they will take no notice if it becomes apparent you are engaging in activities like sexual activity outside of marriage, celebration of Christmas, birthdays ans so on. The less association you have and the longer you have been away from the meetings then the more chance there is they will park a matter until such time as you make some kind of return to the congregation.
In reality there is a mental association about being inactive and irregular or non meeting attendance and given they typically go hand in hand then that's not surprising. Therefore the combination of no FS and meeting activity is often what Witness will mean when they consider someone "inactive".
To be frank, if you have stopped going in FS and stopped meeting attendance then I don't think it is reasonable to conclude that lack of contact from people in the congregation or awkward moments out and about where people avoid you is deliberate shunning. In their mind, you have taken yourself away and people don't know what to say and how to say it. They don't know your reasons. Of course, rumour and gossip abound. People may be making assumptions but in terms of people making a positive decision to shun you then not everyone has the time and inclination to give it active thought - they could just be embarrassed at what to do and say when they spy you down the aisle in the supermarket after not seeing you for six months at the meetings. Stupid I know, but remember where you were before you woke up.
In my experience of observing "affirmative action shunning" of inactive and non-attending ones to date, it would tend to be either by over zealous ones who have heard some rumour about the actions or attitude of an inactive person or by family. Some families and individuals are super self righteous and avoid contact with a family member no longer attending meetings regardless of the lifestyle of the person.
More likely there will be active shunning when the person is doing something like living with someone else. To date I have noted this as most likely when self righteous family members take it on themselves to avoid contact.
The current talk doing the rounds at the RC about shunning inactive ones known to be engaging in wrongdoing repeats older WT policy. The reason it sounds new is because the WTS has not said anything much about it for a while. I suspect as well there is a fear that it's only a relative minor that are shunning inactive wrongdoers and they are seeing more people take a fading strategy thereby helping family members avoid the issues associated with DF/DA.
So for the purposes of the talk, the definition of inactive is used in the broad rather than procedural sense and reminds the faithful that those who have slipped away and doing what they want can't avoid the net of shunning. How many sheeples actually consider this when thinking of whom they might need to shun now and don't now end up actively shunning those who have simply got on with their lives outside of the org is a completely different matter.