15 R2, upgrade motherboard to a newer model?

It's a very risky gamble.  Though the chassis are similar, there are very often small changes to the board dimensions, the mount points and the location of the external ports such that unless you're up for an engineering challenge, it won't be a drop-in replacement.

The other issue is economics: these boards can easily exceed $1,000 -- and for that very few suppliers will give you more than a 90-day warranty.  If you've got that much to spend, you may be better off buying a pre-built desktop (building one yourself these days will likely mean winning the lottery for the GPU and some CPUs) as your stopgap.

Between the economics, the warranty aspects and the engineering issues, it's not a practical upgrade to attempt.

Hi @DragonRWGM  all of the motherboard components are soldered on, the only option is to install a replacement motherboard. The mundane Alienware 15 R2 motherboard Intel options are Here. Currently, the best solution is to get gaming laptop with AMD motherboard from different OEM, whose purchase price is more agreeable and their CPU does not run hot at 100ºC, etc. 

The R2 board is a completely different design compared to the R3 and R4 (which aren't too dissimilar from one another) so you're stuck with that one unfortunately. 

I was just looking into it... I know they’re pricey but didn’t want to replace the laptop yet... had mine paired with a 2070 super before I regrettably sold it back in August anticipating the new cards and building a tower.... the current Alienware towers don’t appeal to me right now because of the cooling and if I build a system it’ll be a 3090 or 6900xt which they don’t even offer. Looking for higher refresh 4K+ gaming at this point. With what’s rumored to come out next year I wanted to hold off. 

Hi @DragonRWGM  Nvidia GeForce RTX 3090 and AMD Radeon RX 6900 XT, more than one GPUs are for Workstation PC, and with Intel's fading reputation from excessively hot CPUs, the AMD Workstation is currently the serious gaming enthusiast's choice. Next year a wide choice of similar and cheaper GPUs will make appearance. 

Which is why I said if I do... and I would be doing high res video rendering too but wanted it to be capable of gaming. That’s why I was asking the question in the fruit place just to see what I can do in the meantime as the next gen stuff that’s been leaked sounds insane.

In simple terms no. It wouldn't be advisable and its too expensive.

Plus the way the original chassis for the R2 was designed for the M series of GPU's and not the 10 series. Plus you got battery and M.2 Placements. Screen connectors and whole lotta other stuff you need to work on.