BTC will still survive without other cryptocurrency, but it'll grow really slow.. and since growing it via alt-coin trading became impossible, there will be so many people left it behind because of the slow growing progress. Finally, there will only serious btc-lover who still uses it.

I consider altcoin to be sometimes positive because you can test or observe some inovations and their development on alt-chains, without risking on running the same modifications
on live bitcoin blockchain. Who knows, maybe some of the good features some altcoin's have get implemented to bitcoin as well.
In any other way, especially in speculation and investments, i wouldn't even touch altcoins as i don't consider them to be nothing more than for testing purpuses only, whatever they claim to represent..

sorry i have to correct peoples terminology, because if bitcoin (the currency) is to go mainstream, then the community needs to start understanding the terminology better, by avoiding words like crypto, virtual, digital.. as they are vague and wacky words common people wont distinguish between fiat and blockchain based currency. and also separating bitcoin the currency vs what some people have in the past called bitcoin the protocol.

again correcting peoples terminology, as it will help explain it to common folk in the future

I think altcoins do provide a benefit, bitcoin is not going to be altered that much but with altcoins there is the room to use the blockchain in ways that bitcoin does not, for example proof of stake is one feature which a lot of the altcoins have been using over the past year or so.

Up to now though we haven't seen many altcoins really breaking out on their own, litecoin is the little brother of bitcoin just hanging about and then doge went mental for a while but has settled back down, don't get me wrong there are some altcoins out there that might break on through to the other side but for now they seem to be a way for people to quickly make a profit off of bitcoin.

i can see them proposing good solutions to some problem that may be related to bitcoin, and did take a big profit from them, but i still find that the majority where there only for stealing bitcoin quickly

they were , after all the most prominent way of stealing bitcoin, in a "manner way" we can see

for example i'm not sure if without doge, the overflow of newbies would have happened anyway...

what if...

starbucks, walmart, 7eleven created a loyalty card system.
1% of all purchased gets converted to an altcoin chain,
EG
for every $1 spent puts 0.01 loyalty coins into an altcoin address linked to the customer.

with 1 coin valued at $1.
people can buy loyalty points(coins) like saving up for christmas, but the coins can only be spent instore.

instantly a coin like this will get recognition, without customers having to know about the techy stuff in the background. and making this coin more popular then bitcoin.

retailers would love it. because they wont need auditors or security teams, or having to claim it on their IRS reports, as its not fiat

Many people trade bitcoin with altcoin. Without those altcoins, the need for bitcoin will be reduced. The bitcoin price will drop.

Altcoin is pretty important, because Altcoin enliven the existence of Bitcoin.

Bitcoin is unique and is valuable and will not only survive but also succeed with or without altcoins.These are alt coins which are dependent on Bitcioin so far and their value is set up on the base of Bitcoin.Bitcoin without Altcoin will be same I dont see any effect.