Things are changing. Back in 1976 my Hebrew teacher (a polish holocaust survivor turned Messianic Christian) would have Pesach sedar every year and there were few who acknowledged it.
Since then we have had many hagadahs in many places with up to 250 mostly protestants attending. Most churches in this area have Passover every year apart from what we do. We have used the service as an object lesson concerning Mashiach for many years.
Mind you. We are not talking about morphing into the old covenant with NT overtones (although that is happening also). This is a true searching out of the roots of the faith and realizing that Mashiach Yehosuah is the king of the Yehudim and Lord of the Cosmos. The true seeker will not soon be able to gain say the roots of the faith and our being grafted into the commonwealth of Israel. Simultaneously he will not be able to adhere to the traditions of men whether they are found in Christianity, Judaism or any other spiritual path. These are exciting times of discovery for those who dare to not shrink back.