If Wasps ARE to build a new stadium, and within that 3 year deadline, they, in effect, have a couple of weeks over 3 and a half years to get it completed. It took Edinburgh 1 year and 15 weeks from start of building work to completion at Murrayfield. So, from now Wasps have two and a quarter years to:
Locate and acquire a site
Get all the planning permissions
Get contractor quotes and sign contracts
Get work started
That is a very tight schedule. Unless it is a site that is already designated for outdoors sports with parking and facilities (unlikely), that means a new site. The only way that can happen in such a short time scale is if such a site is already on an agreed local plan, or some local plans are already proposed and agreed by the local council. So, some weeks ago I looked up and down the Oxford corridor (essentially, the Chiltern railway line Oxford - Banbury - Leamington, and the M40 J8-15) to find any such plans. One mooted near Kidlington, but nothing on paper/submitted.
The other is Warwick:
https://www.warwickdc.gov.uk/downloads/file/5228/community_stadium_project_site_master_planLooking at the plans, some sleight of hand is taking place here by WDC. Erecting a 5000 capacity (one stand, rest is terraces) ground, with limited parking (but maybe they could do a deal with National Grid, who have a massive car park there), and behind it an athletics track. I suspect to replace the ageing track at Edmondscote (where I used to do athletics when I was a youngster at school), which I assume they would then build housing on, to part pay for the new track project.
Of those plans, some of it (if you view the map) 5, 6, 7 and 8 is either now built or underway. I did check for planning applications, and those parts have approved planning applications. That allowed me to see that none of the other parts have had planning applications. There is also a new SEN school there, to link with what I know now as Evergreen School (that site was Round Oak School, which was built on the site of a school I started my teaching at, years ago now. That new school will allow the council to close their other SEN school in the North of Warwick, where I guess more houses will appear. It's all about the money.
There is a lot of land still unused there though, so a bigger stadium could be built, to meet the 10k RFU Premiership rules.
Even so, joining in to that construction and making changes would likely still take a year, even then. Tight for timing, but possible. I know that 'Brakes' are desperate to get out of their Harbury Lane football stadium site. I am not sure who owns it, but I can see planning applications for houses there, and maybe a (much needed for safety as it is a massive accident blackspot) roundabout on the Fosse Way/Harbury Lane corner of that site.
I know logic has not a lot to do with things, but wherever Wasps land next year to play, they can't stay long.