We leased our 2018 for the exact reason you specify. I suspect you are not looking at the buying incentives properly though. I see $1,500 for retail, the dealer can print a Smart Vincent report showing all rebates you qualify for, which include a higher rebate if you take the normal (non-subsidized) finance rate, which you can then pay off days later (and keep the rebate). The tax credit is $4,607 I believe. There are other fees incurred with leasing that you don't incur if you buy.
In my analysis (A-Plan), I will be saving close to $2,000 by leasing vs. buying, assuming at the end of the lease I purchase the vehicle. If it's worth more than the residual value and I sell it, then in fact I will make more money. The rebate for purchase at that time was $3,000 if I recall properly, so if yours is that much lower than leasing is even more attractive.
Can you keep this for 10 years? Maybe. However, you'll find that well before 10 years this car's PHEV capabilities will be a joke as compared to new vehicles on the market (my opinion). We kept our 2010 Fusion Hybrid for 9 years, selling it to buy this vehicle. Repairs were very minor (rear brakes) in addition to oil changes and tire rotations/replacements. Just before we sold it, it had a major suspension problem, possibly brought on by Michigan potholes, that was nearly $2,000. I would expect the battery would have lost considerable capacity near 10 years.
I plan on keeping ours for 3 years, then buying a hybrid / PHEV SUV for our retirement.