Assuming that, nowadays, BTC's hodl could be as long as 5 or even 10 years from now.
How long is a long time hodl in alt-coins?
For example, if I'm looking to hodl ARK/STRAT/XMR, what is the right time-frame? is it just for a few months to a 1 year, or can I leave them for 5 years with the hope of weathering the storms and coming out strong?
And besides, do these kind of coins have a 5-10 year lifespan?
Well depend on your strategy investing on there and how much will getting profit from there, you must choose the target taking profit include cut lost before buy the altcoins, if you looking for short profit use time prime one day up to one week, but if you looking for long profit with big amount, you can invest for couples years later. So choose your target first.