Not a cellaring question, but this forum may have the best input. Local brewer has a Kolsch style I enjoy that is seasonal. Thinking about buying a case to keep in the basement to enjoy over the next 3-4 months. Will it hold up? It's a bit on the hoppier side as far as Kolsches go, so I know that'll drop off a bit.
If you want to preserve freshness of any beer, refrigeration is better than "basement" storage. 3-4 months is pretty much under or around the standard "shelf life" period of many US brewers, macro and craft --- but results vary, of course.
Agreed. The beers flavor will change- how much and to what is not yet known- so you should be prepared for that. I would imagine it might get a touch maltier, of course this is going off my experience having 6 month old Big Sky Summer Honey. If you don't have a garage fridge, I would say this is a good reason to hit up Craigslist/OfferUp and find a reasonable fridge for ~$80. Or if the brewery kegs this kolsch, go that route and drink off that for a while.