Thanks for the reply! That is definitely a very valid concern. I have personally noted that BTCUSD may have double bottomed, and may make a steep recovery, but it is a little early to tell.
BTC dominance is also at an all time low, pictured here:

Thus one may surmise that a correction/return to BTC's strength may be due. In these senses I totally agree with your concern.

My thoughts is that the three coins listed above are strong enough that they will withstand or keep pace with the growth of BTC, if indeed BTC has double bottomed. Then the gains will be nullified but the losses will be as well. If everything works out perfectly (which it never does!) I hope to complete these swing trades before BTC's prospective run-up closer to the end of the month.

As always, it is a good idea to hold ~20-30% BTC and ~15% Fiat to balance out one's altcoin portfolio, and make discounted purchases during corrections.