I don't have the same current situation, but my parents have a place in Florida that has quite a high market value (property taxes alone would be north of $50k/year without homestead exemption). They could end up selling it before passing on, but I doubt that, given their affinity with the property (they built the house, essentially their 'dream house', and it does have a killer waterfront view of the bay/islands).
When they pass on, it will be a significant expense to maintain it for myself and my 3 siblings. I have a feeling that one or two of them (basically, a spendthrift sister and half-spendthrift brother) will be utterly opposed to selling it, but my sensible sister and I will see the absurdity of paying all of that maintenance and expense when it can hardly be used that frequently, given careers and family activities. By selling the place and divying up the shares, a 3% WR alone from each person's share could afford their families a trip to pretty much anywhere in the world for several weeks in fairly generous accommodations - all without the hassle of real estate taxes, hurricane insurance, upkeep, constant worry about nothing happening while it's vacant 90% of the time, etc. In our personal situation, I don't feel the cost is justified for how little time I would use it.
You say that he won't become wealthy, but will earn a decent living...if his share of the cottage is going to take up (for example) 10% or more of his after-tax income, he needs to really think if his emotional attachment (and his limited use of the property) would truly justify that large of an expenditure each and every year - plus the eventual assessment for rehabing/extensive repairs.
You mentioned they might rent it out - but you also mention it has a limited use window due to not being insulated. If it's rented out, then truly how much 'family time' would the family get out of it? If they only get to use it 1, maybe 2 months a year with renting it out, is it truly worth the hassle, expense, and upkeep?