Obviously this is still just an allegation.
For it to have gotten this far, it is far from an allegation. The issue will be that Tigers have not immediately fessed up to the totality of it, which means they are hiding something, and know it is not to be found in the official 'books'.
No player wants to stick their hand up and say, 'It was me wot got £xxx,xxx, and I know these players also did ...'
To do that is to end their career, and the careers of the others, including any who have retired in to public roles, plus the tax implications if they didn't declare it all. So, Tigers have known for some time (had the 'nod') that they were under scrutiny, and had time to hide the obvious stuff. It will go down the same route as the Sarries thing did, but this time round the punishment will be far harsher. After a few months the Prem will announce they have found £xx m of irregularities relating to a certain year, and fine Tigers a huge amount and take 50 points off them.
Then, a month or so later, they will announce further allegations, because Tigers will not admit to anything. They will keep quite. They will protest, just as Sarries did, the unfairness of it all.
And so they Prem will ask them for the 'real' books, which Tigers will refuse to provide. And then, without relegation, what will the Prem do? They cannot let Tigers get away with it, and must be seen to be 'fair' to Sarries.
Permanent exclusion from the RFU? Possibly. It depends how Tigers play it. Damned if they do truly reveal all, and likely damned if they don't.