BTC technicals are against $20,000. I don't think holding now is a good idea.
Maybe a good idea is to move the money from BTC to altcoins.
Possibly, but it's a risky move until the ALT/BTC uptrend is confirmed. If BTCUSD continues surging above $20K, those pairs are liable to bleed back down as ALT/USD pairs stagnate. If BTCUSD crashes, altcoins are liable to crash harder too. In both cases, you'll be losing BTC.
If BTCUSD fails near $20K in the short term
and ALT/BTC and ALT/USD pairs spike upwards (like March 2017), then hell yes. That's got "altcoin season" written all over it.