In the last bubble it took 2 years for bitcoin to recover, and similar thing may happen again. Of course everything is possible in crypto and bitcoin may recover faster, longer or never.
The altcoins I think are likely to follow different pattern. Eos already surpassed the bubble peak and many other third generation projects may die or explode much earlier. If a third generation finishes their project and offer better platform they may surpass bitcoin.
The best thing is probably to diversify and gradually enter the market and have enough FIAT to buy if cryptos dip even more.

I am a big believer in Distributed Ledger Technology and think the overall market will go up, but about any particular currency we don't know, and that is true even for bitcoin and etherium.