In as much as Bitcoin controls a high level of cryptocurrency, altcoins are indispensable.
To my little knowledge on cryptocurrency there are altcoins for a lot of uses, some for medical use, some for advertising, some for gaming and so on. With people having interest in this areas to spread cryptocurrency we can take advantage of this opportunity it doesn't have to be all about Bitcoin all the time.
Though the problem with altcoins is the turn out of the coin after wards and the responsiveness of the owners. But if investors or crypto addicts can engage more in altcoins this will boost altcoins and get more organisers active and spread cryptocurrency more