The true answer is we have no idea which way it is going to. Brining in Tripper could spur AWB on like Telles did Shaw that may happen. But it could also knock his confidence there a countless exmaples of players been dropped or another playing being signed in their position and their form taking a huge nose dive ( A few examples of this: Martials form went through the floor when they brought in Zlatan and gave him his number. I don't think Hinze reacted well to the signing of Evra. Remember how Evans form dive-bombed from being pretty great for 18 months only to be dropped the moment Vidic was half fit, )
Neither you or I, or anyone else in this forum have any idea how AWB will react, and probably even Ole and AWB himself doesn't 100% know as he has never really been through that and even if the player had all the good intentions in the world but when it came to it and he had another player breathing down his neck for the place he may play havoc with his confidence as the brain is a very werid thing.
We also don't know how Tripper will fare. He will be 31 in September, there was definitely occasions in his last season at spurs when he was off the pace he is now a few years older and has to re-adpt to the premier league and play as part of a back 4, which while it is full of talent if you take AWB out of it none of them you would describe as pacey.
Plus we have to take into account trippers' age and contract demands. There are very few effective fullbacks in their mid 30's, just because of the sheer amount of ground you have to cover in the role in the modern game, so Tripper would be a very short-term signing.
Personly I think unless we got trippier on a very club friendly deal I don't think it makes good business sense, (the numbers quoted 20 million and around 100k a week for about 3 years are ridiculous for a reserve right back in his 30's) I also don't think risk of upsetting AWB a 50 million pound investment is worth it for such a short term buy.