Eth has plans for scaling too so they are going to stay. I see them resolving their issues faster than BTC at the current rate with the entire Bitcoin political sausagefest fiesta. They been trying to fix the scaling issue for 2 years but due to infighting it never got resolved.
For Eth, everyone rallies behind Vitalik so what he says pretty much goes.
In any case, the top blockchain platform I see are:
1. BTC
2. ETH
3. IOTA (huge future potential)
No reason why Waves/Lisk/Antshare, etc., can't be 4th. Don't see Waves overthrowing ETH, however -- due to first to market for smart contracts.
Man... your 3 coins already are at the top!!
Not a huge gain forward, besides the market (in this case,why not put 100% in BTC?)
The higher the risk, the higher the gain. It's a good rule of thumb.
Mitigate risk with coins which seem to show a broad acceptance (LTC, STRATIS, WAVES).
Pick some with low MK to maximize potential.