For a boxed processor, the warranty is three years.
This will tell you which processors are currently supported under Windows 10.
Yes, it will still be supported for the next few years.
I do not understand your concerns. Really, you should be concerned with what DELL will support. It is their laptop, and there is nothing you can do about the processor they soldered down in their laptop. If the processor fails tomorrow, it is Dell's problem. If the processor fails 2 years from now, it is Dell's problem. In no case is the processor Intel's problem, as there is nothing Intel can do about Dell's implementation.
You failed to mention if you have dual graphics. If you do, great. If not, you may find support for your graphics as an issue in the next few years.
A laptop with an i7 7th gen processor "is current" and you should be fine. We see users on the forum with laptops that are nearly a decade old, and still working well (although graphics support is typically an issue).
How is that for speculation?
Because the processor is soldered to the motherboard, you have no separate warranty from Intel; you only have the warranty that you received from the laptop vendor (they, in turn, have the warranty from Intel).
It's just my opinion, but if this vendor's warranty is not on the order of three years, then you should not have purchased from this vendor. These scummy companies giving only one year (or sometimes even shorter) warranties are building absolute crap that they know won't last much longer than that). My rule: if it isn't coming with a minimum 3 year warranty, it isn't coming into my home.
I was not trying to blame Intel, I asked Dell about it and they said they are unsure how long the hardware will be supported. The two graphics cards I have are an Intel HD Graphics 650 and an Nvdia Geforce 1050. So I do have two graphics cards if that's what you mean by dual graphics. The laptop is two years old and the warranty expires next year, thank you.