Given the nature of this game, anything other than a full and free implimentation (though possibly requiring the use of a module slot or whatever) will probably generate just as many complaints and 'boycotts' as no implimentation at all.
Thoroughly disagree with that assessment.
The current state of affairs is that there is no 3rd person view (obviously). Any boycott or complaints about the lack thereof has already occurred; the only noise left active are those that would want only 1st person view.
Full and free implementation would draw the most verbose amount of criticism, at least until the playerbase rebalanced to the new norm (i.e. people get used to it and the people that would quit over it has quit).
But addressing the community's concerns with the desire for some form of third person view would yield the best results.
The key is to understanding what is important and what isn't... to sort the signal from the noise so to speak.
In my opinion (and determination); that signal is that first person needs to be kept competitive and viable (or even as the primary form of gameplay), without forcing players to compromise between toggling 3rd person on and off (similar to the issue with pay 2 win consumables; essentially not creating a system where players are without competitive option to keep with only F2P items).
Everything else is just a form of noise; ruins the immersion, against what was stated in their initial development posts, etc. The game isn't fully immersive, although it trends towards it, and obviously developers should reserve the right to reassess their designs upon new information and directions.
Bearing that in mind; keeping it offline is one solution, and making it available only to solo players is another (although somewhat compromises the absolute wall of keeping first person competitive - but I think it's a pretty acceptable one).
The main problem at this point is that anyone that really wants 3rd person has already been driven away; their voices are silent, so most people that remain are the 1st person die-hards that demand that the game stay exclusively 1st person... and as a result are in something of a fevered echo chamber where a large proportion of members aren't even willing to listen to anything to do with third person view (whether or not it can be implemented in a manner that doesn't impact upon their gameplay).