Do you think altcoins can survive without bitcoin leading the way ?
Some will survive but not all of them will. Those altcoins that has great community and valuable asset to the crypto world are the ones that will survive even without bitcoin. The ones that has real use or those coins that are valuable to a company and mostly relying their services there. But majority of them are riding and relying to bitcoin's lead.
will the bitcoiners that lose faith go into altcoins or will they
just cash out and take profits ?
Majority will just hold their bitcoins whatever sequence or scenarios will take place.