why do you have to sell Altcoins? I think it would not hurt if you hold both of them and that's can produce benefits 2x fold. but if you don't have money and want to exchange all your Altcoins for BTC then I think that's not a problem either because BTC remains a promising investment in the future. this is not the time to sell but HODL and BUYING.
Because he is obviously expecting that when halving happens, Bitcoin will boom. Many alts will ride the wave for sure, but some will wilt as well and it's better to have 1 sure thing in your hand than 2 that of which only 1 is a sure thing. Holding doens't always work for alts as most of us can attest.
Nothing is assured when we do talk about the future.The market can either go along with the hype or would just simply go to opposite ways if we do talk about Alts price.We cant really tell if this time they would correlate or go along with btc price or would go to the opposite way.Its a matter of risk handling on a certain individual.
If you can see the advantage on your side then why not but as said i would choose up on having some alts in my stash yet you arent only focusing on single, just be sure not to go all in and split
on several top alts.