What kind of returns would satisfy you?
Personally, I’d be thrilled with a 5-10x overall gain, though I do have a few altcoins I’m planning to hold longer, aiming for the possibility of a 30x or even more.
The way the market is really looking right now, it will be really stunning and excitement if any alts can do more return on investment with guarantee without sacrifice their investment as trial on different project, that will make people invest on altcoin in particular and don't have to spread over their investment on coins that doesn't have features. The funny thing about this is the way altcoins bleed at the slight correction of Bitcoin market.
If you hold into altcoins, you don't really need another person opinion as to when they want to sell their coins, investing in the first place should have a determination when you really wanted to sell and not just buy your altcoins and looking for other people opinions on the coins. Sometimes, you might be surprised that your calling an end to holding coins might be better than someone that has been there before and that's because nobody can really know when to sell on all the altcoins.