Holding FX risk is typically not compensated for by a long term positive expected returns from that exposure. Therefore the common wisdom is to try to match the currency on your assets as much as possible to the currency of your liabilities/future expenses, unless you have an opinion on the direction of currencies and want to bet on it.
From your post it is not clear, whether you would continue to accumulate wealth after moving to EU or are going to live out of your savings or will face significant expenses in EUR like buying real estate there. Is is absolutely certain, that you are going to move to Europe? 5 years sounds as a pretty long horizon. Is there no possibility to need the money before that?
Based on your explanations, it would make sense to move at least part of your assets in EUR. How much would ultimately depend on your answers to the above questions. You might want to consider the following with regard to your idea to trade EUR fx futures:
- The only known to me EUR future contract, the one listed on CME, offers high liquidity only in the next end-of-quarter maturity. It means, you will need to roll your contracts every three months to avoid high bid/ask spreads
- Futures mark to market every day. This means that if the USD strengthens substantially vs EUR, you might need to liquidate part of your other holdings in order to satisfy margin calls (with all possible tax implications from that)
- by being long EUR and short USD on your hedge, you accrue costs, roughly equal to the interest rate differential between both currencies, currently ca. 2.15% p.a. if the spot rate does not move. You would have those implied costs, regardless of how you decide to implement your hedging - using futures, buying EUR-hedged versions of your investments or something else.
- the currency, an asset is denominated in, can be entirely different from the actual economic exposure of this asset. For example, if you hold an emerging market equities ETF, this will be denominated in USD, but the actual economic exposure will be of the various emerging market currencies, held within the vehicle. Same holds for commodities. When the Brexit referendum results were announced in 2016, FTSE 100 stocks shot up to compensate the sharp drop in GBP, simply because many of the FTSE 100 stocks are international companies, which do not derive all of their business out of UK. You might need less hedging that you anticipate in the first place, depending on the currency sensitivity of your assets.