Nah, it doesn't worth a bit. Every cloud mining company will be collapsed before you get your ROI.
Stay away from life-time contracts especially. It is a lie.
I do not hold hashing power longer than 3-4 months. Any S7 hash I buy on Hashnest will be sold at a profit long before the block halving next summer. Talking about trading, not holding GH/s long term. You are right about life time contracts, they are designed to benefit the seller. Anyone who buys now at any other provider than Hashnest e.g. Genesis Mining will have their contracts cancelled after the block halving when fees are greater than profits.
Another route that some take is to buy the newest and best hardware as soon as it hits the market. Many who took delivery of S7's this month will only mine for 4-6 months then sell on Ebay.